I've had similar problems with Humbrol clear, over Tamiya Olive Drab, where the MicroSol/set burned into the clearcoat, leaving a white tidemark.
I recovered it by:
very very carefully sanding the white tidemark/puddle with one of those 4-sided nail buffers from the $/£/€ store, used damp, not wet, so as not to soak the decal or clearcoat.
Allow to dry for days!
Respray with a good quality varnish.
As has been noted Future is acrylic, is subject to the vagaries of moisture, humidity and Decal set!
I tend to use W&N Galeria or Minitaire Satin, as Original (transparent) Future is all but unobtainable in the UK, it's chief benefits was ease of use & cheapness!
Other options are:
Vallejo Gloss Medium (I don't get on with it)
Microscale Micro Gloss
Mig Gauzy Agent
Plan on allowing several days between paint, gloss, decalling, & finish coating, to minimise issues.