I can't claim to know this part well, but the task name in your screenshot matches an older report, vatesfr/xen-orchestra#7496, where Importing content into VDI XO CloudConfigDrive also sat at 0% forever on XO from sources.
In that one the host's self-signed certificate was being refused, and the only visible sign was a DEPTH_ZERO_SELF_SIGNED_CERT line next to importVdiContent in the xo-server log.
Nothing showed in the UI at all.
Since XOA works for you with the same cloud-config, how each one trusts the host certificate feels like a plausible place to look first, though I could be fully wrong about that.
Could you check your xo-server output while one of those tasks is stuck and paste whatever importVdiContent line comes up, along with your commit number?
If it reproduces on another host or a fresh build, that would make a solid GitHub issue, and a mention to @Team-XO-Backend might help in the meantime.
