Edited: See #54586 (comment). There is some issue with dotnet watch and projects in a home directory that is not in the usual location (possibly related to directory symlinks).

Original report:

I have seen a few messages in the aspnet gitter but I think it might be an isolated problem, not an issue. I hope if someone else has the same problem, they will google and find it here and then we will be able to tell if it is an issue or a problem with my system. As for 5.X it worked with Mojave through 3.X-5.X. At 6p2, it worked on Mojave but once I moved to Catalina, it stopped working.

Moved to fresh new mac on Catalina and it also doesn't work here, since .NET6p2 all the way to .NET6p5 (current).

I have tried all variants of the watch command using absolute and relative path, project v.s. solution, as well as the different delimiters like -- run and more on .NET6p5. Have exhausted every combination. It does not detect additions, deletions, or changes in files: .css .razor .cs, even the Program or Startup files. It does not detect even when a file is moved, renamed, added, or deleted.

Probably separate issue: The watch command causes these two errors in browser console:

* Assertion at /__w/1/s/src/mono/mono/metadata/assembly.c:1374, condition `<disabled>' not met

542256 @ dotnet.6.0.0-preview.5.21301.5.js:1

ExitStatus
message: "Program terminated with exit(0)"
name: "ExitStatus"
status: 0
__proto__: Object

Moved these notes from the end of: dotnet/corefx#41963 at the tip from @danmoseley

Linked comments:
dotnet/corefx#41963 (comment)
dotnet/corefx#41963 (comment)
dotnet/corefx#41963 (comment)