Quick question about grounding a 250 ex

Will a need for the extra ground be a cause of my issue? If I run a bead on a flat weld I get a nice bead. However if I try to run a bead on an inside corner joint the metal only heats up and warps until a hole develops. No shiny puddle will form. My 250EX didn't have this issue before. Could there be something inside dirty that causes this? It's not the gas or technique. Thanks for all help.

Nothing in a power supply would cause something like that. Typically inside corners trap argon, and require less flow to perform the same as a flat weld.
It always helps if you list your settings and the material you are trying to weld.

Forget about "the extra ground".