Is this a modpack or mod issue?
(if something is screwy using a certain mod, then send the bug to the mod dev first.)
modpack

PLEASE MENTION IF YOU ADDED ANY MODS.. ESPECIALLY SODIUM, IF YOU DON'T, IT MAKES US VERY GRUMPY
nope

Modpack Version
(any bugs using a non-up-to-date version will be asked to replicate with the most up-to-date release)
2.8.4

Describe the bug
A clear and concise description of what the bug is.
Using 4 inferium blocks and 1 master crystal in a portable crafting station will delete the master crystal

To Reproduce
Steps to reproduce the behavior:

1. place 4 inferium block and one master crystal in a portable crafting station
2. craft
3. receive prudentium block
4. dont receive master crystal back

Expected behavior
A clear and concise description of what you expected to happen.
Should get the master crystal and the prudentium block

Screenshots
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Logs
(you can use https://paste.alloffabric.com)

Additional context
Add any other context about the problem here.

not a tech reborn bug, it happens in molecular assemblers too, and also when trying to normally craft essence blocks with the master infusion stone

This can be fixed by pasting this code: https://pastebin.com/d7L2nvpm into a notepad file then saving it as a .js file and moving it into the kubejs scripts folder

Awesome, which of the three script folders?

• client_scripts
• server_scripts
• startup_scripts
  Many thanks for the fix.

Server_scripts I believe

Made no difference, one craft and the infusion crystal was consumed and as you said, the same behaviour can be seen in Applied Energistics.

The script only fixes it for block crafting I think, and I'm not sure if it works in auto crafters, if you aren't playing on a server try putting the script in client_scripts

Indeed, it does, more likely to be a tech reborn bug.