I reported this as a visual bug before here, but now I’m realizing it’s not just a visual bug! When the troops are stuck, your heroes can not gain mana anymore!
Thanks for reporting, please submit a ticket through the affected account with as much detail as you can provide (time with timezone and date please) How to Contact Support (Version 31 Onwards)
Thank you for the report @Xiao! This issue should be fixed in the upcoming update (version 33).
Marking as solved in the V33 Update: