Copy page to another recently created space is not possible

A few days before updating Confluence from 5.10 to 5.10.1, i was creating a new space DOCS55.
Then i started to copy pages from the space DOCS to DOCS55. Worked all fine, no problem.

Since the update to Confluence 5.10.1 - when i try to copy a page from DOCS to DOCS55, the UI to Copy doesn't find the space DOCS55. The field to select the space is a "autocomplete select field". When i manually add the space DOCS55 and the parent page to copy to - the button Move - to execute the copy is disabled.

As a consequence we cannot use the copy function anymore for the "new space".

By the way ... the issue seems a bit similar to another one - CONF-43037 - which i have reported a few days ago.

This is really blocker for us.
I guess i could copy pages with the CLI, i have to try it out. However, not all of our editors can use the CLI.