Minimised windows in spaces

[iStudentUK]

I'm struggling to find any information on an issue I'm with spaces.

I have two spaces set up, and pages is set for space 2 only. I have many documents open and some are minimised. If I select one of these minimised documents from another space it sometimes opens in that space and sometimes opens in space 2 as it should.

I'm confused as to why it only intermittent, which suggests to me it is not just a setting somewhere.

Any help would be great, this is quite annoying!