Airbus A350 LNAV problems

Hey everybody. I’m having a problem with the Airbus A350 AP. Anytime I fly the A350, I climb to about 3,000 then I turn on AP set V/S to 2800, set speed to 220 till FL100, and turn on my LNAV. As soon as I press LNAV, the plane starts banking left and right. It starts out subtle, but eventually causes the plane to go down.

My Device is an Iphone 11, about 1 year old.

Attempts: Reset App, cleared everything, Deleted and Re-installed.

Sounds like a tricky situation, would you mind sharing the replay file from one of these times using some cloud storage service or for us to have a better understanding of the situation?

Sorry, I would but I reset my app as an attempt to solve it, let me add it onto my topic

Thanks for your help, seems like all I needed to do a force reset

As requested