The other possibility it halyard wrap. This happens when the halyard lead from the head
of the sail to the sheave is nearly parallel to the forestay. The furling
operation may be trying to wrap the halyard around the forestay rather than swivel around the forestay.
Profurl is supposed to be immune to halyard wrap (their assertion), but is easily checked when you furl the sail. Watch the halyard to see if it starts to move when the furling seems to bind. This condition can be relieved by changing the halyard tension, but severe cases require a block or fairlead below the sheave box to pull the halyard away from the forestay.