Same problem here. I can get playback from Windows Media Player & web browsers, but it just drops out/hangs in any DAW. It happened right after the Windows 10 April 2018 feature update. Probably due to the new ability to route audio devices on a per-app basis in Win 10's "Settings>System>Sound>App Volume and Device Preferences". I'm temporarily using my old Tascam US-2000 with no problems.

Looks like Tascam is working on new drivers, but they've been painfully slow with updates the last couple years:

"[Updated] Information about Windows 10 April 2018 Update

 SUPPORT

2018-05-11


TASCAM Engineering is already hard at work on new Windows 10 April 2018 Update for our products.
We are planning to announce the results of verification as soon as possible in this page.
Many thanks to our loyal users for your patience and understanding through this process."

(EDIT): I'm not allowed to post links here yet so Just add the "https:" to the beginning of this URL:
//tascam.jp/int/support/news/5536

pcooke9,
 
 Welcome to the forums from Cakewalk.  
 
Thank you to the update from Tascam about their drivers for Win 10 1803.

Interesting that it broke the driver for the 16x8 and not the older models, My us1641 is working as always after the update. Are you saying the 16x8 has a software mixer? that would be the difference I guess. 

@pcooke9: Nice find! Unfortunately, rolling back the Windows update doesn't help the situation. So I guess we're stuck until Tascam releases another update.
 
@Cactus Music: The 16x08 does have a mixer UI included in the software. Pretty sweet - looks like this...
 


 

So I just plugged in my old M-Audio FastTrack interface and it worked like a charm right off the bat. So it certainly appears to be a Tascam -> Cakewalk issue.
 

OK... I'm not very computer literate, but I read that rolling Windows back to the previous build would correct a lot of problems.  After finally figuring out how to do the rollback, I did and EVERYTHING IS WORKING AGAIN!!!  The Tascam US-16x08 is working fine!  Hope this helps others.

Thanks guys, glad I could help. I just hope they release the new drivers soon, cause I really don't wanna deal with rolling back the Windows update. I have a friend who needs to track some death metal guitars & I can't get the US-2000's RTL any lower than 12ms.

You might want to flip the Driver Settings in CWBL over to WDM/KS (?), let the Wave Profiler routine do it's thing, then see what your input/output options are.  I've had trouble with my US-1800 in the past and had to run in WDM/KS mode for a while.  It worked fine. YMMV...

That Tascam support link was updated the other day, but unfortunately it says the same old drivers/firmware for the US-16x08 have been validated and are "OK".  I beg to differ, lol.

Finally figured it out. It was the Mic Permissions in Windows Privacy Settings.


(EDIT)
I didn't have to allow access to the Mic before the Windows 10 April 2018 Update, so I didn't think to check the Privacy Settings. I also don't need to enable any specific Apps under "Choose which apps can access your microphone"; I currently have all of them disabled. *Also ignore the fact that I spelled "necessary" wrong in that pic, lol.