Bcrypt using 2080ti slow

[Claven99]

I have a relatively new PC 9900K/2080ti, running Windows 10, plenty of memory.

Installed latest hashcat and find BCRYPT H/s too slow compared to benchmarks.

GPU at 750 H/s (CPU at 332 H/s)
(command line hashcat64 -a 0 -m 3200 hash.txt found.txt wordlist.txt -O -w3 -D1,2,3)

Sample hash is $2a$10...
Benchmarks I've found suggest figure should be considerably higher for GPU (though many benchmarks don't show $ rounds)

Tried installing CUDA SDK - appears to have no effect.

Searched throughout forum - no answers found.

Comments/suggestions appreciated.