As said the best way to fix it right now is to use the latest (3.4) apex plug in and to flood your cloth mesh with 0.001 weight before painting to ensure all your vertex are exported in the apx file (so UE4 can actually read it).
I’m currently testing it and it seem to work though I admit its quiet a hassle specially the old collision ragdoll now pushes the .001 vertices =/, hopefully nvidia will change the way the plug-in exports the apx on a future release.