3.7.86 system search editing broken?

In a previous version of RT, I edited two system searches:
Search - Unowned Tickets
Search - My Tickets

I did this so that I could add “Take”, “SPAM”, and “Resolve” columns.
As part of the upgrade to 3.7.86, I’ve noticed that the   that I
put in place of the column name has apparently been URL-escaped. So, I
tried to edit these searches again and was surprised to discover that
the Query Builder didn’t show any query at all! Switching to Advanced
mode revealed an empty query, too. I kind of expected to see a message
in the logfile, but there was nothing. Have I found a bug?