Warning: File modified after build started

[Valiant]

I'm getting this warning for several files in my project:
Warning: The file "filename.htm" has been modified after the build started.
The error can be repeated for several files. The most I have seen is 30 different files listed.

The odd thing is the files listed aren't ones I've been working on.
The warning is more of an annoyance than any problem I can find in the output, though it's concerning to see 20 or 30 warnings listed in the Builds window. When I look at the file attributes for the files listed in the build log, the date and time stamp doesn't reflect that they were changed.

I've had this happen on Flare 2019 and Flare 2020, but it has surfaced in the last couple of months.

[Psider]

Perhaps investigate if there have been any antivirus changes? (Maybe it's started scanning the new htm files created during the generation process and causing Flare to think the files have changed) I've seen a number of oddities caused by overzealous AV over the years.