Upgrade from 2.7.2 to 2.8.0 iBGP not working anymore (kernel does not want FRR/BGP routes from forti)

[div444]

Hi there,

Before going deep in technical details here is a summary of the config and of the issue

Config:
Many pfsense boxes connected to one fortigate throuth ipsec in full mesh mode, using iBGP.

Issue
After upgrading pfsense from 2.7.2 to 2.8.0, pfsense does not want to consider iBGP routes anymore from Fortigate: pfsnese BGP table is correct but kernel does not want to use it and uses default routes.
However between pfsense and another pfsense no issue, iBGP still works as usual. Issue is only with Fortigate with pfsense 2.8.0.

Investigations and result
Of course I googled a lot, used many AI (may be not enough) but till now I did not fix it

Current workaround:
Revert back in 2.7.2

May be the solution is obvious and I dig too much ....
If needed I can give all technical details about this issue.

Thanks