Since today I can no longer log working time directly in Jira (JSM & JSW) - the "Save" button is inactive, although all mandatory fields are filled in.

I usually use the keyboard shortcut 'q' for quick entry, but it no longer works this way.
It also doesn't work if I go through the menu and select "Log work".
Affects Jira Service Management Issues and Jira Software Issues.
It still worked for some Issues in JSM today, but not for the majority of Issues (JSM & JSW).
But I can't see any pattern.
Most recently it worked for all Issues, including last Thursday, September 5, 2024 (my last working day).
Time tracking had already been activated and possible for years.
However, we have not made any changes to the permissions in our organization.
Our only applicable workaround at the moment is to book working time via "Timesheet" as a feature from the "Time Tracker" plugin from third-party provider "Tempo".
(Feature "+ log time").

Hence the question:
Has there been a Jira update in the last few days that has a negative impact on this (bad fix)?