I can set a repeater offset from Chirp, and that works fine, but it displays incorrectly in the SHIFT setting on the radio. It displays as 7.60MHz for every repeater frequency. Apparently, visiting the setting in the menus gets the really bad value (7.6MHz) applied until you leave the channel and come back.
Reversing the repeater frequencies (assigned to P1 on the microphone) shows the right frequencies. Programming it from Chirp as a split (instead of +/- offset) works, but still doesn’t show correctly in the menus.
The radio also only allows setting by 10kHz manually, so setting my 605kHz shift for W3GMS is impossible to program from the radio.
There’s already a bug filed for Chirp.