Gypsum board & re-emulsifyable water based drywall mud have NO place in any tile installation . Especially the compund. In the tile world thats a double no and a sure bondbreaker.

Houzz full of expert advice i!

@Mint tile Minneapolis What would you recommend filling it with instead?

Have you considered replacing it with a version designed for larger rolls? Then you might be able to just place the new holder into the recess instead. I know AC Products makes one, though not sure what size hole it needs.

@artemis78 Thanks for the suggestion. I would as a last resort, but trying to update the look of the bathroom so hoping to patch it up somehow if possible.

Oh dear, you may only have needed a roll extender to allow your old tp holder to accept the larger rolls. They're pretty cheap & you can get one free from Charmin:

https://shop.charmin.com/charmin-roll-extender/

They worked fine for my old ceramic installed-in-wall tp holders.