Disappearing Clown Loaches (long)

Last November I purchased 4 Clown Loaches for my planted 55g tank which also
had 2 Bronze, 1 Albino, and 4 Elegans Corys, 6 Danios, 4 Adult and 3
juvenile Angels, a few Platies, and 2 SAE.

At first the CL's were pretty invisible then started to come out.
After taking up residence in a resin log (about a month later), I would only
see them in pairs (the 2 bigger ones, or the 2 smaller ones).

A month ago it was time to put out the pond fish from my 105g (also
planted), so I moved everyone except for some of the platies down to that.
We have a large resin driftwood piece in the 105g with lots of holes/caves
etc, another of the resin logs that the CL's loved, so I thought they would
go into that.....Wrong !

I hardly see them now. I see one on it's own out and about. I didn't see the
others even at feeding time.
I was so worried after a week I took out the resin driftwood which had to be
half-emptied before the clowns came out, the smallest seemed to have shrunk
to just a head and shrivelled body. This one was eventually found dead under
the filter :-( Al took shelter under the fixed internal filter (Juwel tank)
and after a while disappeared again, I'm assuming, back into the driftwood.

Could they be getting stuck in the drift wood ?
I don't want to keep stressing them by moving it all the time ?

Peter