which UG4 do you have?
on your proxmark can you do hf 14a reader -@ until it finds stable placement, if it struggles to do that i recommend getting a passive repeater, either the board for the proxmark or a standalone sticker.
no need to worry, this is fixable.
Worked like a charm! Thank you! For posterity, this was a FlexUG4 sold in the most recent batch in October, with the improved antennas. I got a stable point with the command above, then was able to wipe it with script run hf_mf_ultimatecard -w 1. I assume now I should at least be able to write the old tag back to it with the Flipper, but if I wanted to get better with my proxmark as well, what was missing from my command above? It was script run hf_mf_ultimatecard -u [my uid] -t 1
yup!
glad to hear it’s all sorted!