1) The president doesn't have a magic dial to bring down prices, and
2) Trump loves tariffs which have inflationary effects no matter how you spin it
So all the complaints about high prices was just for show since they don't actually care.
EDIT: 3) Inflation was a global phenomenon and the U.S. was actually outperforming most countries in bringing the rate of inflation down.
You might think that this isn't a very satisfying answer for those who aren't already onboard.
I'm not saying that this is a steel-man rational argument for Republicans, but I think it is a popular narrative to quell cognitive dissonance within their ranks (applied to other issues as well).
The pain is easier to endure if you truly believe that the pain is for your own benefit.