'From' field/drop-down disappearing when creating new email in Mail app

[ISignedUpToAskThis]

Apologies if this is a known issue, I couldn't find anything obvious from the front page or searching.

Every time I open Mail and go to create a new email, the 'From' field which has the drop-down menu to pick which alias you wish to send from appears for half a second and then disappears.

This means I can't select which alias account to send an email from.

I've tried signing in and out of iCloud, and there doesn't seem to be any option in 'Window' or 'View' to toggle it on or off.

Anyone else have this issue? Am I missing something completely obvious that's causing this?

I'm on 26.0.1 using a M4 MBA.

 

[adrianlondon]

I've never looked at that drop-down for the "From" option.

My compose window has To, Cc, Subject, From. I assumed that appeared automatically once I created an alias as I don't remember having to enable it.

(I don't use Hide My Email, apart from on this screenshot to, ironically, hide my email address 😁)