Hey Pat,
You don't tell us whether this is a global or app-specific macro.
We need to know:
Keyboard Maestro Version.
System Version.
What software-context you're running the macro from.
Is the macro always active?
Paste Keyboard Maestro Version and the macOS System Version Automagically
You may want to peruse the troubleshooting section of the wiki.
You can also use the Assistance (wizard) in the Keyboard Maestro Editor Help menu.
If you can make a video of this happening and post it on YouTube, so we can actually see the process it might help.
There's quite a lot you can do to track this problem down, but we need more information than you've provided in order to give intelligent advice.
-Chris