Broken upload of software images

I am trying to upload new SW images to cnMaestro On-Premises 3.2.0-r5 but I always end up with some error. When uploading from local file the upload seems to be completed fully but then it throws the “Failed to update the JSON file” error. I was able to succesfully upload the tarballs for synced and non-synced N ePMPs but never succeeded with the “img” files for AC ePMPs, neither the tarballs for AC F300-13L (ePMP-AC-F300-13L_F300-25L-v4.7.0.1-RC6.tar.gz).
Software images I get offered to download from cnMaestro cloud are quite old (AC images are version 4.6.2) and the process of adding these images ends up with this error: “Error while uploading device software image from cnMaestro cloud.”
I cleared the browser cache several times, tried on 2 different machines, switched between Firefox 110 and Chrome 110, deleted all the cookies but with no effect.

We’re having the same problem.