Skill unbinds after area change if requirements are only met via Specialization Points

If you change areas or relog while meeting the following conditions, the skill bindings for skills set to be used only with Weapon Set 1 will be removed.

Conditions:

Set up your passive tree so that the required Attribute for the skill gem is slightly (about 1–4 points) below the requirement.

Then, use Specialization Points to gain the missing Attribute needed for that gem.
(In my case, I obtained the required stats from different parts of the tree for each weapon set.)

Next, set the skill gem to be usable only with Weapon Set 1.

After binding this skill to a slot, changing areas or relogging will cause that slot to become empty.

(I am not a native English speaker, so this report was written using automatic translation.)