There is a bug caused by this potion quoting my reply from another thread:
The bug is still in the game. It happened to me yesterday twice at least with superior tawny owl potion. To my knowledge, i you enter combat use the potion it works fine, but if the fight ends with the potion still active sometimes it bugs. I suspect it happens when a cutscene follows the fight with the potion active.
Example. Quest Last Wish. Fighting a the Djin. I use thunderbolt + tawny oil and burst the djin down within 20s or so and after all the cuscenes with Yen end the stamina is stuck and does regenerate at all. Meditating and loosing the pot buff doesnt fix it. Reusing another tawny owl after that gives you regen from the potion itself but not the standard regen.
This happens also other times. Tawny oil is great potion i was using a lot but upgrading to the superior version broke it for me.
Do you still want to send some save with this bug to your email?