Problem with searching

I’ve been having a problem for a few days now – it’s not finding my messages after entering text in the upper right corner of the search box.
When I expand the options and enter the search field, it finds the messages.
For example when write in search box: example - search nothing.
When write: subject:example - then will find.
Everything was working fine before.
I also verified the databases. Unfortunately, that didn’t help.
I don’t see an option to attach a screenshot here.