This GitHub issue has some information about the problems.
Assuming the translation is correct I find it a bit odd that Vasilena Yosifova, who is shown on LinkedIn as a Marketing Specialist at pCloud AG, is not only "... in charge of pCloud support." but also entrusted to reconfigure pCloud's entire infrastructure.
... I restarted and reconfigured the entire infrastructure (integration with the WebDav API) and it immediately resolved itself.
Anyway, the below post shows that if you know how to to edit your Joplin database and you are willing to take the risk you can over-ride the block by changing a key in the settings table.