Adobe Reader DC & Sharepoint: Data is write-protected

Hello,

we have a Problem to save our PDF via Sharepoint if we have opened it and did some changes.

Problem happens since last Novemberupdate i guess: 18.009.20050

Following errormessage appears:

Document cannot be saved, data is write-protected or actually in use by another user. Save your data with a different name oder to a different location.

I have already tried a bit:

-upgrade to newest Version

-adding the sharepointlocation to trusted securityzones

-unchecked enhanced security in settings->security(enhanced) or uncheck secured mode

-googling

Sorry for my bad english

Thanks a lot & with kind regards

Robert S.