Same
problem here. We have enough space, filestore is reachable... It
occurs, when we upload several files at once - ony the first one (pdf)
is uploaded, the others (jpg) not. Several jpg files without a pdf work
as grouped upload.
The last change to the whole server
occured yesterday - RS was not working anymore, because of missed files
in php 7.0 (reason unkown), the inhouse support switched to php 7.2.
afterwards (apache settings) and now RS is running again. Perphaps the
problems are connected, since it's new since the php switching?
Offtopic: Why there is no edit function of own postings, It is very unhandy to correct typos or unclear explanations here.