I haven't seen this reported in the other threads yet - I'm not sure if it's particular to my hardware, or just my general workflow, but it's very consistently reproducible.  Basically, if you're recording a track (audio or midi), and the following three conditions are met:

• The 'Take Lanes' toggle is 'On'
• The record mode is 'Comping' or 'Sound on Sound'
• There is existing data in a take on the track during which you'll be recording

As soon as recording stops, Sonar crashes.  The crash doesn't occur in 'Overwrite' mode, or if there's no data already present, or if the take lanes are closed/off.
 
Version:  Sonar Platinum 21.11.00 Build 25 x64, Lexington
OS: Windows 10
Event log (Application):
Faulting application name: SONARPLT.exe, version: 21.11.0.25, time stamp: 0x566ebb2c
Faulting module name: ntdll.dll, version: 10.0.10586.20, time stamp: 0x56540c3b
Exception code: 0xc0000374
Fault offset: 0x00000000000ee00c
Faulting process id: 0x111c
Faulting application start time: 0x01d140ae682dfdde
Faulting application path: C:\Program Files\Cakewalk\SONAR Platinum\SONARPLT.exe
Faulting module path: C:\WINDOWS\SYSTEM32\ntdll.dll
Report Id: 4c00173d-a3c2-4756-a143-3248df465343
Faulting package full name:
Faulting package-relative application ID:

Hi. It seems like ntdll.dll is Windows related.
http://www.computerhope.com/issues/ch000960.htm
All the best.

I just tried this very quickly in Lexington but am unable to reproduce I recorded a single track of Audio, stopped recording.  Set up a loop then tried recording Audio and Midi in comping mode this occurred without problem.

I opened a file started in Lexington 64 bit the previous day and started to replace my scratch piano part (Ivory Piano). I started at the beginning and played the whole song through 1x and at the end of the song, I hit stop and I got the Sonar Fault reporter box with a crash. I opened 32 bit Ipswich and had no problems for the rest of the day
 
The update right before Lexington had a known bug with some plugins. I would get a loud hiss from my Ivory Piano. Even when Sonar was stopped. I was hoping Lexington with all the hype would be really stable. I've never had any version of Platinum crash like this especially under a very light load (3 audio tracks). I've reverted back to Ipswich.

I've been getting crashes once every couple of days. I cannot repeat or explain.

gswitz
I've been getting crashes once every couple of days. I cannot repeat or explain.

Was this happening with previous updates or just Lexington?

Cannot reproduce. Followed your recipe, works fine. Same Lexington build.
 
In the past days I have been messing around heavily with take lanes in Lexington to learn the stuff, so I have gone through all sorts of combinations. No crash.

gmp

gswitz
I've been getting crashes once every couple of days. I cannot repeat or explain.

Was this happening with previous updates or just Lexington?

I'm not sure. I began noticing crashes when TH3 first came out, but right now I'm mixing a project without TH3 and it is crashing too. So, since late October? In not sure.

I've suspected TH3, AD2, and Rapture Pro. None of these are in the current project. Do I'm suspicious of the "performance enhancements".

At one point I spent ten hours or so trying to replicate a case where I play guitar through rapture pro past the end of an AD2 midi drum loop. I was not able to replicate, but in my attempts, I did not actually play, I just recorded.

http://forum.cakewalk.com/m/tm.aspx?m=3330958

When playing, I have had this crash case a number of times. I don't know if it is a true true unrelated case or not.

Yep. Similar issues here. Been crashing during audio recording or when you hit the space bar to stop recording.
Happening every day 3 out of 5 takes. Have tried different things - can't work it out. Started happening after I upgraded to Lexington.

oztadpole
Yep. Similar issues here. Been crashing during audio recording or when you hit the space bar to stop recording.
Happening every day 3 out of 5 takes. Have tried different things - can't work it out. Started happening after I upgraded to Lexington.

The good news is that since you're not alone, it'll get fixed likely soon. Did you turn in a bug report? If not I'll send in one. This may even warrant a hotfix, since there's so much hype about how stable this update is supposed to be and that stability was one of the prime focuses. I've reverted back to Ipswich and after your report I'm glad I did. Thanks for chiming in.