App not recognising custom cards

Hey all

I’ve been using the mobile app on my phone for months and has been been working pretty much perfectly for me but I’ve just got hold of an Amazon fire 5th generation tablet to use as a permanent screen for home assistant.

My problem is that all custom cards don’t work in Lovelace. I get a custom element doesn’t exist error on all custom cards.

I can’t understand why everything works on my phone but not on the tablet.

I’ve tried editing existing cards and creating new ones but nothing works

Any help would be appreciated. Thanks