Unable to pick up call using BLF key if handset is picked up first


I have UCM6202 with 5 GXP2135, all hardware has latest available firmware installed as of today.
all 5 (1000-1004) extensions are part of one pickup group so they can answer each others calls when needed and all 5 have BLF keys configured for the other 4 extensions.
Everything is working fine except one very annoying issue that we can’t seems to figure out how to solve.
Say IVR calls comes in for extension 1002, 1001 knows that no one is there and they can answer call that was meant for 1002 from their own extension by pressing 1002 BLF key that is flashing red during incoming call to that extension. The ONLY way to answer is to press BLF key BEFORE picking up handset, this in turn puts call on speakerphone and handset can be picked up at that time. Well, this is super annoying as all they want to do is pick up handset first and press appropriate BLF key, this does not work this way at all. If handset is picked up, they simply get a dial tone as one would expect but pressing flashing red BLF key does absolutely nothing at all as if button doesnt work. Wondering if anyone ran into this issue before? We do have support ticket open and they saying that what we want should just work, picking up handset and pressing BLF that is.

GXP2140 won't pick up parked call unless "End" is pressed first on handset

We have the same issue - GXP2140 won't pick up parked call unless "End" is pressed first on handset

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