Uploaded file registered with incomplete extension

I experience a problem with OJS 3 (latest stable version): an article was submitte, in word format. But I can’t, as a redactor, download it or send it to review. When clicking on it, I get a 500 error message.
After looking at the logs, the problem seems to be a discordance between the real name of the uploaded file and the one stored in the database. It appears as if a too long filename was used…

The real filename in the OJS directory arborescence is

and the log says

[Fri Feb 15 12:04:04.558213 2019] [php:notice] [pid 27878] [client] FileApiHandler: File /Partages/OJS/journals/2//articles/33/submission/33-13-193-1-2-20190214.do does not exist or is not readable!, referer: http://info124.pharmacie.univ-paris5.fr:1987/OJS/index.php/UELC9/workflow/index/33/3

which is the correct path, the correct file name except the extension is .do instead of docx: the last two characters are missing, making the file impossible to find!

By making a symbolic link from the real file to the one asked for in the log, things get in order. But it’s not a very practical solution.
Any hint about what’s going wrong?
Thanks in advance