GPS Issue - Wrong 9, mid round.

Today I was playing 1-18 at my golf course which has 27 holes. All was good until I got to hole 17 at which point the GPS showed hole number 8 on the third 9.I saw no way to get to the correct hole as all the software would allow me to do was to go up or back one hole not jump to another 9.

I have not had this problem before and my software is up to date. Any suggestions?