Modpack version
1.65d

Can the issue be reproduced?
Yes

Logs
Logs show no log output

Issue
When inserting into the fuel slot of vanilla furnace, mystical agriculture Ultimate Furnace, tinker's construct Heater, cooking for blockheads Oven it gets dropped on ground or returned to inventory.

--Breaking Block & rebooting server did not fix

Gif:
https://media.giphy.com/media/RGplFfPE0P2KHLpAuz/giphy.gif

Looks like this happened in #651 but breaking the block resolved it. Unfortunately not so in this scenario.

Thank you for the report, I will investigate the issue.

Happens only if you don't have Wireless RF Battery nearby. Not intuitive behaviour, but i guess, thats not a bug.