Sealant recommendations

Hi, I’ve been using Effetto Mariposa Caffelatex sealant in my 38mm Gravelking tyres, but have noticed that rather than stay as a liquid sloshing around in the tyre, it seems to solidify all around the inner of the tyre itself after a few weeks and also, very annoyingly, over the valve hole meaning pumping up the tyre involves poking a stick down the hole (!).

Its not a recent weather thing, its been happening a while. I thought I was putting too much/little in, but that makes no difference so the only conclusion is that it is no use for me.

So I’m after recommendations for a sealant that will stay as a sealant (or suggestions for what I am doing wrong). Many thanks everyone.