Mmm ok i think I get this.
The tenant is still likely using the old vlan subscription (because that's the one that was published first). Since VLAN objects are named identically , the Tenant still thinks it has the correct object .. but since L2 is different, traffic won't flow.
The correct way to address this would be deleting the old VLAN from the tenant, removing publication, and adding it back so it's going to create a new subscription. But that's going to take a lot of effort because you need to remove VLAN from every object first (Virtual Servers, and self IP's - which would require you to assign a different vlan temporarily).
So .. in this very specific case it might just be faster to actually just rewrite the tag in the config file
cp /config/bigip.conf /config/bigip.conf.backup
sed -i 's/tag 1978/tag 978/g' /config/bigip.conf
#repeat w/ other tags
more /config/bigip.conf | grep tag
tmsh load sys config verify
tmsh load sys config
tmsh save sys config
tmsh list net vlan tag
#rollback
cp /config/bigip.conf.backup /config/bigip.conf
tmsh load sys config
tmsh save sys config