AC 3.6.7 firmware only in chibiOS version

Hello,
I'm using last mission planner, and I ugraded to 3.6.7 from 3.6.6 my hexacopter pixhawk FMUV2, and I checked NO chibi OS during firmware upgrade process.
After upgrade done, I see when connected to hexacopter, in the mission planner messages "
chibios" instead of "PX4"
I remade the upgrade many times to be sure that I dont made mistake, by cliking NO CHIBIOS when mission planner promt, and Always it install ChibiOS version.
And now I can't go back to 3.6.6 or 3.6.5.

When I pick previous firmware, even if I check AC3.6.5, it propose only 3.5.7.....
....I Don't found the firmware on the previous firmware link.
thank you for your help.

Start by reproducing the firmware upgrade flow for a Pixhawk FMUv2 with AC 3.6.7, selecting NO CHIBIOS, and then checking the previous-firmware choices for AC 3.6.5 and 3.6.6. Done means the selected non-ChibiOS firmware is installed and the requested previous versions are available for selection.

Written by the indexing model from the issue text.