VST settings changing on rendering song to WAV

Hi guys,
any help with this would be greatly appreciated. I was using a flute sound in the synth vst “tera 3”. The sound was changing to a very sine-y sound upon rendering the whole song to WAV. What I noticed was that the envelope time was changing from 0.0 (mid) to -0.5 (the lowest setting) for some reason, thus removing the soft attack. I was wondering if the time was synced with any aspects of the song or something entirely different? I tried changing the envelop length manually, reloading the default setting for the synth, and also reloading the plugin, but although it sounded like a flute (as I wanted) in playback, the output rendering was still reverting to the sine-y sound, because of the envelope timing.

Does it also happen if you double click Renoise’s stop button?

No that didn’t effect it, thanks for suggestion.
I’ll update though, I thought of a possible work around, and that was too tie the envelope timing control in the plug in to a MIDI control in renoise. After that idea I went back to the song I was working on and tried a couple more experiments with exporting / rendering WAV from different points in the song and it magically worked, albeit with slightly inconsistent results between rendering. That’s without even applying the “work around”. But it’s going good now. Bloody computers!