Hi!
Helen here for the monday.com team 
.
You mentioned you’re trying to push data from your monday.com account into a Google Sheet-- is that right? I’m wondering if you’re also pulling in data from an Excel file? You mentioned you also have an incoming Excel module.
It might help for me to see your Integromat scenario to better understand why the values are getting lost somewhere in the middle there.
You can also probably click into each individual module to check out which values are currently being held in each (thus isolating the issue to see where the values are being lost).
Hope this helps!
Helen