Which pool are you using in the Multipool stratum list?
In the previous posts somewhere, I have seen that there might be problems in some pools, but for the algo you stated, there's only one pool stated there, i.e.; Nicehash... And everything seems to be working fine as there are ~5 THs working on the pool and mining with SHA256...

Don't know what's the problem with you... Maybe, @marcetin could help...