Flatten/unflatten data and copy composition

Hi all!

I develop an effect plugin.

The problem is when i try to copy whole composition (cntr+c), After Effects send my plugin the following actions:

1. PF_Cmd_SEQUENCE_FLATTEN - here i flatten my sequence data
2. PF_Cmd_SEQUENCE_RESETUP - here i correctly unflatten my data (flatten data in in_data->sequence_data is right)
3. PF_Cmd_SEQUENCE_RESETUP - here i correctly unflatten my data (flatten data in in_data->sequence_data is right)
4. PF_Cmd_SEQUENCE_RESETUP - here i flatten data in in_data->sequence_data is broken (just trash here)

I try to test such usecase (copy composition) for PathMaster plug-in from standard plug-in examples, in_data->sequence in third PF_Cmd_SEQUENCE_RESETUP in broken too...

Any guesses?