There is a workshop mark in the centre field between the figures. I cannot make it out from the images but perhaps you will have more luck in hand.
The possible officina/wortkshop marks for this mint are: A, B, Γ, Δ, ε, ς, Z, H, εΔ
Here is one of mine of the same type for comparison with a B between the figures..
Obv:- IMP C M AVR PROBVS AVG, Radiate, draped and cuirassed bust right
Rev:- CLEMENTIA TEMP, Jupiter standing left with scepter, giving globe surmounted by eagle to Probus
Minted in Antioch (B in centre field, XXI in exe)
Reference:- RIC 921 Bust type C

Regards,
Martin