Possible Regression between 1.28.4 - 1.28.5: credentials set --validator={index} errors

[valefar-on-discord]

A user on discord reported that they have a script with ethdo similar to:

./ethdo validator credentials set --offline --private-key="0x...." --withdrawal-address="0x..." --validator=12345

This works in 1.28.4 but results in this error with 1.28.5:
Error: failed to process: unknown account specifier 12345

Looks to be a result of 9ae927f