Lately, I've been experiencing intermittent connectivity with Sonar and my Behringer X-touch.  Sonar will show it "connecting" but never connects.  Windows 10 status is that it is connected and working OK.  I can uninstall it in the Windows Device Manager, power off the X-Touch and then power back on and Windows will reinstall it.  I can then start Sonar and its connected and works OK.  
 
I've tried a different USB cable and a different USB port on the PC and it makes no difference but as Windows always shows it "working OK" it would seem to point to Sonar??
 

It seems like infamous Sonar MIDI related bugs for me.
"Connecting..." means that Sonar does not receive handshake reply from X-Touch (which it turn can be that X-Touch does not receive the request).
 
I hope you do not have ANY MIDI devices which are not at the same state when you start Sonar. I mean if you use some device in Sonar, it should be ALWAYS on when you start it. If you do not use some device and prefer it is off, it should be ALWAYS off when you start Sonar. Otherwise Sonar becomes crazy and mix devices, especially in Control Surfaces IN/OUT ports (without showing they are mixed). There is no known workaround for that.
 
General "repair" sequence which from what I know has never failed so far:
1) in the Windows Device manager, check the option to show hidden (disconnected) devices. Delete all not existing MIDI devices if they appear. Check for names like "... - 2"/"... - 3" and similar. It is better to uninstall them and install again, as "the first". In doubt, remove all MIDI devices and install them again.
Note: any MIDI device influence how Sonar works with other
2) in %APPDATA%/Cakewalk/<your Sonar version>/ remove TTSSEQ.INI
3) start Sonar and configure MIDI and surfaces.

The only other MIDI device, is my Frontier Tranzport.  I've been using that since the Vista OS days.  Nothing new has been added.  Must be the problems you note in Sonar.  But, it had been working OK for a couple of years and just recently (last couple months) started having the problem.  I'm guessing some Windows 10 update may have added something that is causing the problem.
 

Something else is wrong.  Now Studio One 3 shows the X-Touch but its not working in Studio One 3, and it was before.

fireberd
Something else is wrong.  Now Studio One 3 shows the X-Touch but its not working in Studio One 3, and it was before.

I had some wonkiness this past weekend with my X-touch in Studio One.  I powered it down a couple of times and verified it was in USB mode and then it started working again.

reboot? (both X-Touch and PC)
 
unplug all your other devices and launch app with just the X-Touch connected?

I can get it to work.  I power on the X-Touch, uninstall it in the Device Manager.  Then power it off then back on and Windows detects and reinstalls it.  But, that shouldn't happen.  As both Sonar and Studio One appear to have the same problem its back to (my guess) a Windows 10 issue.  I've had the X-Touch for several years and it worked without problems, this is only a recent problem so I really suspect something in Windows 10. I haven't added or deleted/changed any hardware or software, except Windows 10 updates.
 
Update: Things get even stranger.  Now Sonar is working OK with the X-Touch this morning, but Studio One 3 will not use the Behringer X-Touch when its "installed" as the Behringer X-Touch (and it has been working).  I removed the X-Touch entry in Studio One 3 and added a Mackie with X-Touch send/receive and now its working??????????
 
 

@firebred,
 
I always used the X-touch in S1 as Mackie.  I think I tried the other way initially and it didn't work.

fireberd
I can get it to work.  I power on the X-Touch, uninstall it in the Device Manager.  Then power it off then back on and Windows detects and reinstalls it.  But, that shouldn't happen.  As both Sonar and Studio One appear to have the same problem its back to (my guess) a Windows 10 issue.

I would tend to agree with the Win10 assessment, since I recently encountered similar.
 
I am new to Win10, and in working with my old Saffire the other day I had it come online and "do nothing" - hardware and MixControl came up looking normal, but even an input signal didn't register in either. Similar in that I uninstalled/re-installed MixControl and *poof* it is back online like nothing happened. Win10 has some odd/freaky driver system in the background that I haven't delved into quickly, but I would very much like to find a means to "lock" how/what/when/where it is tapping into this or that. It seems to choose "this" instead of "that" willy nilly at times.
 
In my case, ASIO4ALL is playing into this particular event, and as much as I do like the convenience of working "right away" when no audio inputs are required, I am still struggling with the "magic recipe" to make it not cause a driver conflict. I can (sorta) handle the preferences shifting around, but when the hardware comes up "dead" that is a bit much .

ASIO4ALL can be a hit or miss.  Works great for some, does not work or causes problems for others. 
 
In my case the X-Touch and Sonar seems to have went away.  Last two days its connected and worked OK.  I tried it 3 or 4 times yesterday (from a power on) and each time it worked OK.  Tried it twice this morning and OK.  As its been flakey for the last month or so and now back to working everytime I guess chalk it up to "FM" (effing Magic).