DaVinci Noise Reduction plugin sometimes not working

Hi everyone,

I've been working on a 45min narrative project - applying noise reduction on various clips without problem - but today ~30 minutes in - i try to apply the noise reduction plug in onto a single track audio clip - and it doesn't work. The Effect is listed on the inspector but when you open the controls - no changes are registered. I then apply it to another clip - and it works.
I tried copy then pasting the effect from one clip to another - has worked previously but now when i try to copy it to certain clips - it won't paste onto it.

It seems completely random when the noise reduction plug in works and when it doesn't. When it doesn't apply to a clip - it indicates that an FX is on (but has no effect on the clip) - shutting program down then re-opening - the FX is no longer on the clip. Basically it seems completely random when it works and doesn't - when close then re-open Da Vinci - and try to apply the audio FX to the same clip - still doesn't work.

Using Version 17.4.3 Build 10
Mac OS big sur 11.6

Can anyone help??

Update - some of my video clips are linked to 3 or more audio tracks (2 x lapel audio and boom audio). i have all audio tracks on the fairlight workspace/track list but have deactivated the audio i did not want to use.
i have now noticed when i apply the noise reduction to eg. lapel mic B - the actual noise reduction is applied to lapel mic A which is deactivated.
When i completely delete the unused audio clips linked to the video and then apply NR plug in to the audio clip i am using - it works fine.
I have not worked out how the NR applies itself to the particular audio clip even though I have applied it to the selected audio clip i am using. It decides to apply itself to another audio clip link to the video which i am not using.
Completely deleting audio clips linked but not used for the video - is working for now.
I think it should just apply to the audio clip i have selected and applied it to - even if there are other audio clips of the same recording, not being used in the edit - Da Vinci seems to decide to apply it to another audio clip attached to the same video which is not being used.
Perhaps it can be fixed in the next update.
Audio plug ins - only act on the audio clip that is selected - even if that audio clip is one of several that are linked to the same video.

Is this limited to instantiating the Fairlight AFX as a Clip Effect or this also an issue with Track inserts?

Do third party plugins exhibit the same behaviour or is this limited to Fairlight AFX instances?

What is the Track format and media type? Is this behaviour specific to a particular configuration?

Is this behaviour on a standard Timeline or within nested Timelines?