How can I deselect all images that are marked for export?

You're asking for a basic feature that should have been in there since 2018. 

I have the same issue, sometimes i'll duplicate items not realizing they've been Marked for Export, and then i'll have to hunt them down by doing several rounds of test Batch exporting. Select All-ing doesnt work because the groups have to be all open for the content inside to be selected. I'm really cusious if the designers of XD actually use it.

I think I have a way out,

Situation: I have 10 Artboards where I want to export assets page by page and put it in a folder dedicated to the page...just to keep it organised. 
So When I go to the 2nd board & looking out for a short cut to uncheck the assets already Maked To Export in 1st artboard. How do I uncheck form 1st board?

Solution: Select all in first artboard (Or all artboards), The dash(-) appear on Mark To Export option. It means some assets are selected. So click to appear check or tick mart & then click again to uncheck. This will Uncheck all in just 3 clicks in total.

Click 01: Select All

Click 02: Click Check / Tick on Mark To Export

Click 03: Click again on Mark To Export to uncheck all.
This is the currect solution..

Note: Keep layers of the same asset in group. And do not keep assets inside a group/mask. The you have to manually uncheck by going inside the group/mask.

Ignore this - didn't work!

If you select everything, then toggle Mark for Export on and off would that kind of work...?

Hi Thavilang,

In order to deselect the the asset that you don't want to export, I would request you to select all the objects and uncheck "Mark for export" at the botom of properties panel in Design mode. 

Thanks,

Atul_Saini