I've tried entering
*.tmp; *.bak or
*.tmp, *.bak or
*.tmp *.bak in the name matching field, but simple search only seems to search for one file type at time.
I've also tried advanced find with the filters shown in the screen shot, below. But nothing is found.
The "Opus Manual" menu at the top right of the forum has a link to the Wildcard Syntax which shows the correct format:
No file is going to match
*.tmp at once. The proper way would be:
*.tmp) AND (Time Modified Within 4 minutes)
And you can use Sub-Clause to bracket things so the boolean logic is correct:
Which is the same as this:
Which is the same as this in simple mode: