Cashback sites are a bit hit and miss and need close follow-up.
IME Ebates and Topcashback UK are rather OK, but 100% of ICHG stays must be retro claimed - it may have something to do with the way hotels "touch" RA reservations (upgrades, etc). TCB US - I have less experience, but Radisson stays posted after a while. Worst experience is with Quidco.