Well, it is possible they’re not………..I mean, we all know that Belle (especially) and Neal are often not in episodes. There’s no reason why they can’t not be in this episode ……..Belle wasn’t in 17 and possibly not in 18 (and it appears barely in 19) and MRJ has had similar issues.
If Belle has not been with Gold, and apparently she hasn’t, since he’s still under WW control (unless while WW is away, the mice play), and she hasn’t been with the main group (which she hasn’t), either she’s not filmed at all, filmed very little or……. I don’t know, this just doesn’t make sense. If she’s not with Gold, why isn’t she with the main group? The only thing I can think of is that she’s being backburnered again……..