My "attitude" is simple:
There are hundreds of mail services out there, GD is just one of those, and hundreds of mail apps.
Those mail services and mail apps are able to interoperate by:
1) following standards
2) providing technical information where necessary
There are no issues using AquaMail with real Office 365 accounts. Zero. None.
Now GoDaddy takes Office 365 and "does something" so it no longer works with this particular app (and possibly others).
What is it they did?
Do you expect *me* to know?
How? Crystal ball? Chicken feathers?
GD are (someone there is, hopefully) the one(s) who know what they did, how their "cloud based mail service which sounds like it's Office 365 but clearly not same Office 365 or else it would just work" is different from the original, real, genuine Office 365.
But their support doesn't seem to want to discuss that.
And you don't seem to be willing or able to push them for those answers.
One more time, slowly:
They took Office 365 and somehow made it different so it happens to no longer work with AquaMail (and possibly other apps).
I have absolutely no way to know what they did.
And they are not telling.
They aren't even capable of discussing it at an appropriately technical level: "just use the stock email app" does not clarify anything technical.
A bunch of incompetent clowns (yeah, they're a large company, so OK, "a large bunch of incompetent clowns").
And yes, I read above that you're going to use the "native" email app.
Sure, whatever, if GD's "365" is mangled so only this one choice works, well, what can I do?