Safe mode with open core boot manager

Hey guys, i can't get to safemode in order to revert a OpenCore legacy patcher update that failed.

As far as i read, to enter safe mode in opbm you have to press shift key along with enter in the boot menu (i don't see icons, only letters). when i do that, a forbidden sign shows and the text "support.apple.com/mac/startup". can you help me? i'm really close to fix my problem, thanks to all the wisdom collected in this forum