I had a similar experience in HI Gdansk. The correct hotel and room was showing but the charges weren't correct. Reception couldn't understand why so applied them themselves. They could see my reward wallet on their screens.
Oddly, my emails from IHG said my vouchers had been removed rather than the usual redeemed email. Nevertheless, foilio at checkout showed the rewards correctly as a deduction.
I still don't think they've quite nailed the seemless use of these for us customers.