Hello warrior nagual lady,
thank You for expressing Your concern.
Would like to remind You that endurance elixir have effect over certain number of rounds, could it be that You have exceeded that limit?
If no - what was the effect on use? Item disappeared without effect, effect worn off faster than it should be? Which elixir was it - great, flawless, powerful or simple? Can You provide us an approximate date and time of when that happened?

Looking forward for more information from You so we can resolve the problem You have encountered as soon as possible.

this is interesting, didn't know that endurance elixir had effect over a certain number of rounds, thought it stayed for the whole fight (this is elixir that increases hp by 48% )

flawless ones and powerful, i alternately use, so not sure which one specifically, time wise, about 12 hrs ago from now...but have to admit, that the effect didnt go away immediately but went away when battle was long...just didnt know that it lasted a limited amount of rounds.

Flawless Elixir of Endurance lasts for 70 rounds as stated in tooltip and it seems that You have had a long fight and effect of elixir faded.
Useful tip in this case - You can equip more than one elixir on Your belt and use next one after first fades.