Hello,
as i found out by myself the following things:
It looks like you can not install the older offline-bundle with the update manager -> it shows the new modul is an older version, so you must install it via ssh/ESXI-CLI like this:
esxcli software vib install -d path_to_bundle.zip
But it works also on my site (at the moment 1 DL380 Gen8 tested)
Best regards
Werner St.