Unable to progress on Act 2 Cruel : Ancient Vows Quest

I'm currently on Act 2 Cruel doing the Ancient Vows Quest. I obtained the Sun Relic and silly me went back to Valley of Titans Act 2 (NOT Cruel) and dropped the Sun Relic on the medallion.

It's gone. I realized that I went to the wrong place and I continued on. After getting the other relic, this time I went to Valley of Titans Act 2 Cruel and dropped the medallion. The other half is still missing. Tried to clear the bone pits twice but I cannot find the Sun Relic anymore.

Any tips on how to continue on this quest?