Strange Album issue

Hi,
I successfully created 3 new albums this evening, two of those are sub-albums of the first one.
I then went to create a 4th album, again a sub of the first, but despite several attempts, I don’t get the usual parent album selector, I now get a numeric field, with two toggle arrows to select up or down from zero
I haven’t changed any config.
Any idea why this has happened?

I can’t figure how to add an image of what happens now.
Neil