Can't create new or edit email template

Your software
My Mautic version is: 3.3.3
My PHP version is: 7.4.11
My Database type and version is: 5.7

Your problem
My problem is:
I can’t create a new email template. Channels → Email.
I have three email templates under this section. I can’t edit them either.
When I click the edit or new button, nothing happens. The page content doesn’t change.

These errors are showing in the log:
No entries in the log file.

Steps I have tried to fix the problem:
No clue.

Many thanks for helping

Christian

I have a similar issue. I can preview an email, but changing the URL view to edit results in a 404
https://mautic.mydomain/s/emails/preview/9https://mautic.mydomain/s/emails/edit/9
When I try to change the email from the campaignbuilder the edit url is:
https://mautic.mydomain/s/emails/edit/9? contentOnly=1&updateSelect=campaignevent_properties_email. This results in a 500 message.
When I click “create new email” from the campaign builder I receive a 500 message
Chrome and Firefox both didn’t work
No logs.