Mi8 dipper and e0.13 issue

Hi all,
My MI8 was running lineage-17.1-20201013-microG-dipper. I try to flash e-0.13-p-2020120889008-dev-dipper, in order to go back to /e/ world, but without any success.
The error is : xiaomi.verify_modem time stamp -2.
I was initially with TWRP and start a dirty install, after that a fresh one by format all, and also try with and TWRP release but I have the same issue.

So I’m back on LOS+MicroG 17.1.
Of course I have to reinstall all my apps :-((

I suspect going from Q (LOS17.1) to Pie (e-0.13) is not easy and probably the root cause.
Who knows what means “xiaomi.verify_modem error” ?
Any of you has an idea on that topic?