One of my games uses a lot of embedded links to show things like maps or menus for locations, along with visible images, in the initial posts of location threads.

I (co-GM) needed to relist one of these posts somewhere else in the game, and in the process used one of the One-Off Identities to do so, copy-pasting the entire original post so that the embedded links still worked...only, it didn't. Instead of popping up a nice, neat clickable 'Menu' link, it threw out the entire format code for it for the players viewing it. As a Bonus Awful, the links looked perfect to both myself and the other GM. This was the same on both mobile and desktop, on responsive. We only realized the links were busted when a player finally mentioned it after several days. /embarrassed

The embedded links worked again once the primary GM went and edited the posts to be posted as them, instead of by the One-Off Identity I had created. No change at all to the body of the post or links themselves, just changing the author of the post from a One-Off to the primary GM and hitting 'Update Post'.

1) What caused this? Was it my using a One-Off, or not being the primary GM in the first place?

2) Is this a bug? I don't see anything in the FAQs about GM access that make me think that the ability to embed links shouldn't be the same for all GMs in a game, and seeing that only GMs can create One-Off Identities, it doesn't seem to make sense that using those would prevent a link from appearing properly.

3) Why did the link APPEAR to be working for myself and the other GM, even though it wasn't right for players viewing it? (This wasn't a responsive vs. old site issue, as we had a player using responsive check it once being alerted that the links were busted, and it was busted for them as well.)

No definitive answers, just a few ill-educated guesses sprinkled with semi-tame conjecture ...

As far as I know GMs are the only ones who can post links, but I don't know if that extends to Co-GMs.

My best guess is that One-Off Identities are treated as having GM access at the time the post is being written, but then revert to NPC access once actually posted to the thread.

Which makes sense to me as the aim of the One-Off identities is to save the GM having to set up a throwaway NPC character, so the assumption would be that such a post wouldn't/shouldn't be posting links and should be treated in all ways as an NPC - though while the post is being written, GM access overrides all (since the GM might decide at the last second to post as GM instead) and final access would be  only be set in stone at the time the post was submitted.

If the One-Off Identity links are rendering OK for GM and/or Co-GM thereafter, then that'd again just be because of the GM elevated access.

And yes, I'm pretty sure it's always been that way on the old site too, so concur, not a Responsive bug.