after last update Dynamics Sales HUB all lookup fields do not provide available list of records without click on Enter button. When I click on magnifier I am receiving only recent records (I received all related records before). This function stopped work after Wave 2 release last week. This is an annoying slowdown of our customers work.
That is a new feature in PowerApps 2019 release wave 2 Update, and has been generally available in Oct 2, 2019.
If you want to provide some advices to this new feature, please submit an idea to PowerApps Ideas Forum, where is for users to provide feedback about Microsoft PowerApp products. What’s more, if a feedback is high voted there by other customers, it will be promising that Microsoft Product Team will take it into consideration when designing the next version in the future.
I find someone has submitted the same idea, i think you can share your feedbacks to there.