It’s legal – just – but is it right? I don’t think so. Firstly, the minutes of the AGM can’t be approved or otherwise until the next General Meeting, so it kind of makes sense that they aren’t sent out until just before … but then how are to people who weren’t at the meeting to know what was decided?
But this building manager is only the employee of the Owners, not the other way round and he has to do what they collectively want. So this is what you do, at your next EC meeting (you do have EC meetings, don’t you?) you agree that in future a summary of all General Meeting and EC meeting decisions will be sent out to all owners within two weeks of the meeting. In fact the minutes of the EC meetings (not general meetings) have to be sent out within 14 days by law.
Then you order the manager that the next AGM will be held in the evening at a time that suits the majority of owners rather than them.
If he refuses, sack him. The tail must not wag the dog.