Is it hot in there? Is your fridge or other appliance either in it or recessed/vented in it?

It is not hot in there. Our refrig is recessed into it but there is a wall in between and it is not vented into the pantry.

Is your pantry ventilated? Could that be the problem? You don't complain about odors, though, just things going stale.

Where was your old pantry? In a basement? New pantry location?

Here is a link that might be useful: Thread: I have a pantry suggestion... Ventilate!

It might not feel warmer to you, but try a thermometer to read the temperature there compared to your previous storage area. If it is items like bread and chips, then maybe a separate storage container for them might be helpful.

There are some odors but it's from onions/ garlic. Not sure there's a lot to be done about that except put them somewhere else or store in an airtight container.
The new pantry is not much different in location than the old ones.
The pantry is not ventilated, but we leave the door open all of the time, so it should be like the rest of the kitchen.
Thanks for that link, looks like I'm not the only one with this issue.