Time problem

I'm sorry if I am in the wrong part of the Forum but I have suddenly come up against a problem with Excel that has never been there before and I wonder if I have maybe pressed some key along the way!
I have spreadsheets where I put the time into a cell in hrs:mins:secs - have been doing this for ages, years in fact, then suddenly last week I formatted the cells as usual to bring up the entry in hrs:mins:secs and every time I enter data, for instance 01:44:15, I get 15:00 showing up in the cell. I have checked and double checked the formatting and it is definitely set to show the hrs:mins:secs as I usually do. What on earth have I done????

Am typing the data - I type it in 1 then full colon 45 then another full colon and then 23

Tried the Ctrl+Shift - no difference. Am uploading the workbook that is affected. Thank you for your help so far much appreciated

Th e format in G column is CUSTOM - mm:ss.
Pl chnge it to TIME and select required format in TYPE.

thanks to both of you for your help. I will change it to Time and use that although I do have to say that I have about 30 of these workbooks and all the others are formatted using the Custom method and they all work - maybe just a glitch but I am truly thankful for your help and I can at least now get these sent off with the times properly in place - Nick