Atr 42/72 f/o mcdu inop

Do you have the same issue if you follow the OP’s steps to reproduce it?

Yes

Provide extra information to complete the original description of the issue:

FO FMC will only select a few pages and once in the flpln page can only access flpln & sec flpln pages. Hitting return just cycles through the two pages

If relevant, provide additional screenshots/video: