Attended Transfer on Yealink T26 not working

[Flora_Yealink]

Hi ,
We have tested it in our side, it can work well, below are the test steps
A is T26 with version 6.73.0.50, register a account 100
1. 101 makes a call to 100, 100 answers the call
2. 100 presses transfer button + 102 +OK, 101 is held
102 rings , 102 answers the call, 100 and 102 are in the call
3. 100 presses the transfer button again, 100 is back to idle states and 101 and 102 are in the call
while in your scenario in the step 3, all phones 100 , 101, 102 will be idle sates ,right ?
If yes, please help provide us below information, config.bin file, pcap trace and level 6 syslog that we can check .
and please let us know how many phones you have ? all have the same issue ? is there any phone can work well in the same scenario ?