I agree. Mojos are a bit like cats, let ‘em be and they’ll usually find their way back.
Certainly don’t fret about it, it’s a hobby, creativeness is demanding, and pushing yourself where you don’t want to go is likely to lead to frustration on two counts, as it won’t go right, and you’re supposed to be doing it for fun.
Reading something inspirational helps, as does a redirection of interest & effort. You’ve done a stack of track building & wiring, which happily seems to have gone very well, so perhaps a loco, wagon, shed, coach, loading gauge, water crane...? Paint a few figures, and have fun posing them in absurd, and in believable groups, ‘til you find something you like... there’s so much potential variety! I’m sure that watching telly for a couple of evenings, deciding it’s all dross, you’ll soon be finding yourself back at the workbench with something different to do.
Good luck
Simon