Thanks, indeed LACP options are correct [1]. The problem doesn't happen when Linux is happily up and running but during the PXE phase (hence also the force-up)Make sure that you've configured the correct options in the bonding interfaces... try something like "mode=802.3ad miimon=100 lacp_rate=fast xmit_hash_policy=layer2+3".
If you don't specify the 802.3d mode it won't send LACP control frames down the wire and thus the switch drops the LAG 'cause it doesn't detect a correct configured peer and it won't risk dropping traffic or worse creating a network loop.
I cannot find anywhere meaning for LagExpiry (the issue only persist with RHEL7 while RHEL8 is fine but of course it might be a timing problem and having a faster PXE like the one in RHEL8 won't trigger it)
[1] m4r1k/nfvi_lab