I bought an ALPINE UP last summer to try on multi-pitch routes for a bit of extra holding power whilst belaying, it generally worked well on a 3 pitch abseil from the Vajolet towers with some new Beal Cobra 8.6 half ropes.
Later on the trip I did a ~25m abseil off the top of the Torre Piccola di Falzarego, and the sheath of the almost new Cobras was slipping & bunching up into the device when abseiling, it was getting so bad that I almost couldn't move and I had to stop several times to push the sheath down the rope core. The Cobras are Unicore too, so the sheath is supposed to be glued to the core.
Not sure what was causing the issue - potentially the ALPINE UP doesn't like abseiling on twisted ropes?
Has anyone else experienced similar? User error, or just inherent weakness of the device?