I have a project with Alexa Mini that I started on ver 14, where I imported Arriraw file natively into the project and it all worked. All files had integrated support (MXF/ARRIRAW development Setting). Anamorphic footages came in as adjusted, without me doing anthing.
Now I upgraded to 15.0 and, suddenly, problems started.
It was basically three:
1) Premiere doesn't remember, or take considerations, of Arriraw input/output setting. Therefore instead of 2.35 anamorphic sizing, the whole native frame shows up IN THE dimension of this 2.35 sizing, so it appears blown-up vertically
2) I tried to start from scratch and imported MXF by drag and drop, or from media browser, but i get import error and can't import them now.
3) Some media which went to media offline, i cannot reconnect due to same error as 2)
Can you check what happened to Arriraw support? based on what I searched I found this: