Working now on this forum. I was sure it wasn't working at the time I wrote this topic. Might be getting crazy.
Sorry and thank you.
PS: issue closed on github.
Some plugins don't seem to be able to update via the ACP. Doesn't seem to be exclusive to particular plugins, but an array of them can't seem to update on different sites on different distributions that I have running.
I see he same issue as @Technowix was just going to report. Plugins that are upgradable for me seem to want to downgrade to previous version.