By default it doesn't look like it was set up for bags, probably because of so many bag addons.
I don't ElvUI so you will have to get the name of it's bag frame(s) and add it/them to the list of MouseLook_FramesToCheck.
Type /fstack
Every frame your mouse passes over will show a tooltip like window with a list of frames under the mouse.
Mouse over the open ElvUI bag frame (asumuing it's a single bag and close to the top is probably best). Find the name of the frame, possibly something like "ElvUIBagFrame" (just a guess).
In MouseLook .lua at line 94 after the text:
"AccountantFrame",
Add the name from /fstack like:
"ElvUIBagFrame",
The names are case senstive:
the line will look like"
Code:
"PetJournalParent", "AccountantFrame", "ElvUIBagFrame",
Type /fstack again to turn it off.
If it uses multiple bags you will have to add the names of each one to the list.