I left a comment about this on the addon page at CurseForge back in April. You told me, "It requires a /reload to be active after the setting is enabled and works pretty fine on my end."

I responded back saying that I tired this and it didn't work. Doing a /reload after enabling the setting didn't work. New Openables doesn't show up on Masque list of addons for me to skin. I have tired doing a /reload after enabling, and disabling Masque support setting. I have also tired doing a /reload after enabling and disabling the skin button setting and nothing happens. I have also tired deleting the addon and all it's setting files from the WTF folder and reinstalling the addon fresh and that didn't work either.

Anyways, hoping to hear a response.

NOP does not add own profile options to Masque but uses the default settings. There is no support for dedicated skin settings.
I was mistaken there: addon options are added. If they are not, that appears to be an issue with your Masque version or profile.
This is with a blank Masque profile:

Hmmm. Alright, so I completely deleted everything New Openables again, and deleted everything Masque as well. No SavedVariables for both apps, a fresh install for both, and I'm still having the same issue. I don't know why you can see NOP on Masque, but I can't.

https://i.imgur.com/x9eyzck.png

EDIT: I'm also using the latest version of both New Openables and Masque.

What do the following commands print in chat?
/run print(NOP and NOP.masque)
/dump NOP.AceDB.profile.masque

/run print(NOP and NOP.masque) simply said "nil"

/dump NOP_dev.AceDB.profile.masque just says:

Dump: value=NOP_dev.AceDB.profile.masque

I needed to correct the second command. Can you retry this please?
I'll push an alpha version with some small adjustment to see if this improves things.

That worked! Thank you! I'm so stoked, I've lived without a skinned button for so long. haha

Thanks for verifying :)