Running app in IDE fails

I’m having a problem running my app while in the IDE. When I hit the Run button Xojo puts up the Progress window and the progress bar in it advances. But then Xojo flashes up another window which, if I look quickly, seems to say 'Build Failed". The box does not stay up long enough for me to see if there is anything else in it that might give me an idea what is going wrong.

I tried clearing the cache(s?) but that didn’t help. Is there anyplace I can look to see if error logs are being generated by Xojo?

Interestingly, if instead of clicking Run, I tell Xojo to Build the app, it builds fine and the resultant app runs. But not being able to run it in the IDE makes debugging tedious so I’m open to suggestions.

BTW, it is a 32-bit desktop app on Windows 10 using Xojo 2017r2.1. 2017r2.0 does the same thing.

do you have any #IF debugBuild pragmas?
perhaps there is something in one that is not compatible with the current environment
those would be skipped over in a true “build”

Make sure a Debug copy of the app is not still running in the background. Look in Task Manager or Activity Monitor depending upon your platform.

@Dave S, @Stephen Koger those are both good places to start looking. Thanks.