SequenceData issue in AE 2022 (Gamma_Table and SmartyPants do not seem to work)

I've successfully retrieved the sequence_data in the SmartRender function using the following code:

PF_ConstHandle seqDataH;
AEFX_SuiteScoper<PF_EffectSequenceDataSuite1> seqDataSuite = AEFX_SuiteScoper<PF_EffectSequenceDataSuite1>(in_data, kPFEffectSequenceDataSuite, kPFEffectSequenceDataSuiteVersion1, out_data);
ERR(seqDataSuite->PF_GetConstSequenceData(in_data->effect_ref, &seqDataH));
SeqData* seqDataP = reinterpret_cast<SeqData*>(const_cast<void*>(*seqDataH));

Since I want to write to sequence_data in the render function, I've set the PF_OutFlag2_MUTABLE_RENDER_SEQUENCE_DATA_SLOWER flag. So far so good.

However, I also need to retrieve the sequence_data in the "HandleChangedParam" function (in response to PF_Cmd_USER_CHANGED_PARAM). Using the same code as above I was unable to get the sequence_data in that function.

For clarification, let me briefly explain how my plug-in works and perhaps someone will provide an alternative way to achieve the same result:

- During render, a (sequence_data) string is set. This string represents text file content.
- When the user clicks on an export button, the stored string is written to file. This is the reason why I need to retrieve sequence_data in HandleChangedParam.

Cheers