I moved T158142 from "Backlog" to "iOS app" on User-Josve05a , then I opened that task in a new tab and removed that task from User-Josve05a. I then (tried to) move T159501 from "Backlog" to "iOS app" on User-Josve05a as well, only to get the following error code:
Unhandled Exception ("Exception") Unable to find object "PHID-TASK-e7exja3qxveh5qxbfuvl" in column "PHID-PCOL-iegs2nmokgb4oatw455g" on board "PHID-PROJ-pvhu7u7ahy32wuyadzui".
Which caused me to not be able to move T159501 until I refreshed the page.