Maybe the EC was not sure if the solicitor could attend till after the paper went out but has sent a notice as soon as possible?
While it might be nice to have notice of an invited attendee, I doubt it is a requirement of a compliant AGM notice; it isn’t in the ACT where I am.
I assume the solicitor is invited to be able to provide expert answers to questions that might arise during discussion of some topic that is on the agenda?