I've been using the Mac version of Microsoft Remote Desktop ever since I switched to Mac.
Currently sitting on this Version 10.9.5 (2179).
Every day I face multiple crashes with it, and they all happen when I'm working inside the Remote Desktop and then I switch to another application on my Mac like teams for example, or Safari, to browse the web.
It will sometimes close/crash the Microsoft Remote Desktop, then I receive a crash report that asks if I want to re-open it and submit a crash report, which I always do.
It doesn't open every time I alt+tab or switch to another app, but in a day, it probably happens 10 times.