Thanks for the answers. Sorry I haven’t been able to answer before but work was pretty hectic last week. Hopefully next one will be quieter ??
I’ve tested with the three plugins, one after the other.
I have the problem with tablepress, the two others being deactivated.
I had (see below) the problem with subscribe2, the two others being deactivated.
I have the problem with Importateur WordPress, the two others being deactivated.
However, some new informations that might be interesting and are highly frustrating:
Some other media seems to be added just fine, even though they are same type and smaller size.
With some other media I have no error message, but the same problem as before, i. e. media upload progress bar stuck at 100%, no image in media library (but media is in library), and media size at 1×1 px when added to a post.
I’ve seen subscribe2 version 10.1 has been released. Updated it but it doesn’t change.
I have to admit I’m starting to think I won’t be able to have it working ??