When a customer dials the main number and dials extension 4 for tech support, it rings 5 phones at the same time. (works)
User A pickup call but customer needs to talk to someone specific, so user A Parks call and hangs up. (works)
User B picks up the park call and talks to the customer. (works)
After user A has already hung up and is ready to receive calls a new customer calls and dials Extension 4 and everyone's phone rings but not user A phone.
User A phone will continue not to work till user B hangs up the call that was initially received by user A.
Group delay setting has already be changed from 15 seconds (default) to 0 seconds.
Strangely enough, if someone dials user A extension directly their phone will ring as expected, just not when they dial the group extension.