I'd like to say I have the answer but I don't!
I'm getting this too after writing a bespoke signature this morning.
I have seen this before and fixed it but I can't for the life of me remember how to fix it now, I have tried to run a McAfee Agent Update Task but this has had no effect.
Which Content Version does ePO Report? Which Extension Build is in use? Do you see similar when looking into the McAfee Default IPS Rules policy?
Do you have a screenshot?`
Ah, mine has just corrected itself, in ePO it is now reporting with the correct Signature name, I guess it just takes time to replicate out between the server, clients and agent handlers.
We found the issue. Our Extension was out of date. As soon as we updated that, the Content Update subtask of our Client Update Task updated the content of our IPS policies.