Can you take a screenshot of this part of the tool?
The way the VESC tool knows which firmware to use, is based on the Hw: [NAME], which in the example above is “60”
If that doesn’t match (because maybe one of their older custom firmwares used a different hardware name) then you won’t be able to update just by clicking upload.
However, if you are sure it’s supposed to be running UBOX_V2_75 firmware, you can load the file manually from the archive @ Index of /vesc_fw_archive by using the “custom file” feature. You may have to update the bootloader (next tab over) if it fails to load, as that was changed for 6.0.
If you do, give Silent HFI a try and post your results in the Silent HFI thread. That’s one of the few ESCs that has both phase shunts and phase filters, so it would be really interesting to see how well it works.