Continuation of archived forum question search-bug-with-exchange-2019
This is now being pushed into CU8 (maybe).
I also received this info from an engineer.
"When testing this issue out, for some reason it only appears to affect “S” and the few other letters that I have tried doesn’t appears to have the same issue. Which is good that doesn’t affect many different scenarios.
It appears that just the “S” at the start of the search query follow by numbers has this issue occur.
When testing out the other letters or different combination of numbers it works. You should also be able to find the message without including the letter “S”."