Rpg Maker Developers Group

The idea at the base of the game I'm working on is that there are a large number of events going on, and there is limited time available, so the player needs to choose which events they want to attend. So I need a time system.
However, for a variety of reasons, I do not want to use a time system based on real time, so I've been trying to set up a step-based time system.
I've based it off SRDude tutorial
and it works... until minute 59 of game time.
After that, it goes crazy.

This is how I set up the common event:


I have created a "watch" item following the example of the video, to check the time, and I have created several events in the map to check how many steps have been taken.
Up to 119 steps everything works as it is supposed to do: after 4 steps the time is 9:2, after 60 steps the time is 9:30
After step 120, everything goes crazy:
at 132 steps I get Day 26: the current time is 2:6
and if I check again, without taking any more steps, I get a different result: Day 268 the current time is 12:6
at 199 steps I get "Day 4246: the current time: is 0:39" and so on.
Btw, this does not happen before step 120, if I check the time at step 60 the risult is always 9.30.

If anyone has any idea what I've done wrong and/or is able to suggest a different solution I'll be really thankful