I cannot find him as nothing in GRO or census. Not possible to know what is wrong. I suspect that he is this Patrick Cronin
1894 Aug 15. Born Limerick
1921 Jun 30. Joined with RIC no 82172 & Adric 1287 (985) . ex-Soldier & Labourer
1921 Oct 28 Posted to H Coy
1921 Dec 23. Posted to R Coy