not had this with kona as of yet and car was sitting without being used much of dec. the bluelink wouldnt do anything bar say it wouldnt heat car up etc. but it swung mirrors and started ok when i asked it, so battery in mine must be ok. (its possible yours is not getting recharged via the traction battery)
my last car, a hybrid chr went through 5 batteries. it was terrible for it.. battery was small tho.
Current Car: Hyundai Kona Premium EV...2 way 40kg hoist
Last Car: Toyota C-HR Excel Hybrid...4 way 80kg hoist