I was Liquid Light's first UK customer back in 1977
Looks like a fixing/washing issue (110% sure). I tried Liquid Light but found I could make a better emulsion myself, however this was a commercial application and I did a lot of research and development.
The problem is the Liquid Light emulsion swells when wet and takes 90 minutes to 120 minutes to wash properly. it's not like RC paper and worse than FB paper.
I'd use a two bath fixer regime. a good rinse then a bath of HCA for 2 or 3 minutes, a 1-2% Sodium Sulphite solution is cheaper and just as efficient, then a good long wash.
Somewhere I have Ceramic tile with a test print and it's not deteriorated since 1977, there's also a print on wood Sealed with lacquer first).
Get in touch by PM if you want I havve over a decade of commercial experience of liquid emulsions and did some trials with Ilford (who wanted to supply emulsion to my company).
Ian