Hi Tricky,
Sorry for my delayed reply and thank you very much for your reply to my questions.
Actually I considered to add timimg constraints to my design but as the frequency is relatively "low" I thought that it may not be worthy. I certainly was wrong so I will start reading about TimeQuest, timing constraints and SDC in order to learn and apply it to my design.
One more question if I may: Another problem that I had (which clearly seems to be the same) is that some register loopbacks that I had on my design didn't work even when the simulation was perfect. I read, I guess in Quartus Handbook, that register loopbacks should be avoided so I added an extra register on the loopback path and an extra clock cycle and then everything worked out. So I would like to know if this register loopback issue could be fixed with timing constraints as well or if I should keep the registers that I placed on the loopback path.
Sorry for all the questions but I still have a lot to learn here :)
Thanks for your time in advance.
Regards,
Javier