Scoll Versions - Publish to new space - Error no 'Complete' Pages

EDIT: This actually was SOLVED. But I maybe will have to ask a connected question soon. EDIT

Hello Team,

we are testing to setup and use the 'Private Master Space approach', one space per version.

Currently on our test environment I tried to publish two separate versions of the master space to 'a new space' each.

Our initial version is v5, the subsequent version we defined as 6.

Note: In all cases below the option "Publish only 'Complete' pages" is selected.

• When I publish v5 and v6 in the production system ('same space approach' yet), both publish fine. 
• When I publish v5 into a new space on our test environment, it publishes fine.
• When I try to publish v6 into a new space in our test environment, the following error message is displayed: "There are 714 pages that are not published, because they or one of their parent pages are not in workflow state 'Completed'."
• I also tried to repeat publishing v6 to the then existing space formerly created; to no avail.

I'd like to add that it says explicitly in the option 'Publish only complete...' that it will "Publish all unversioned pages and versioned pages in workflow status "Complete". Does not publish subtrees of pages, if the root of that subtree is not in workflow status "Complete"."

The subtree-issue never made any difference so far, not in v5 or v6 (v5 true for both setups).

As also v6 usually publishes fine, I don't know what to do.

Thanks for some hints.

BR
Nina