When using fixed positions, the variant i swap to seems to stick to its “non-sticky” position within the document, and stick to the viewport only after animations have finished. This affects smart animations only.
To reproduce: Create smart animated interaction > Apply fixed position > scroll down a bit, and trigger interaction > experience weird jerkiness 
Sorry, no fix, and no feedback from figma on the issue as of yet. Waiting patiently…
@Nicolas_Lebrun As it happened, I found a fix just now: Instead of putting the scrollable content directly in the topmost frame, wrap it in another frame, make that frame the same size as the parent frame, check “fix position when scrolling” to true (So that the parent frame has fixed content only), and set scrolling as desired on the child frame. A bit convoluted and hacky, but it works!
Nice, thanks for the fix 
Genius, thanks a lot 
Huge thank you! Totally worked to preserve scroll position in overlay with variants.
Wow! totally fixed it! thanks.
Just what I needed, thanks!
Thank you for the fix. Worked just fine now.
