I've looked in the CSS of the theme from the app and I see this
/* Table Content */
It just doesn't look like this "Grid" display is being implemented. Everything is "block" which makes me wonder if there's some kind of CSS overwriting the css for the widget
Did you follow the steps here to install the new Atlas Theme modules as part of the Mx 8 to 9 conversion? https://docs.mendix.com/refguide/moving-from-8-to-9#3-7-update-atlas-module-optional
I can definately tell that the datagrid.scss file is not getting loaded from the themesource/datawidgets/web folder. I can see in a blank dummy project it’s being applied in the developer tools, but in my converted project, it isn’t loading these files.
Getting closer. Comparing the two deployment directories…. the new dummy project has two files in the deployment folder: “build_core.html” and “main.scss” file that references css from other themes, including “@use "themesource/datawidgets/web/main.scss" as module7;”
The converted project has only “build_core.html”.
So whatever copies this main.css file to te deployment folder isn’t working in my converted project
I must have done something out of order the first couple of times. What I did that eventually worked (I swear I did this before, but..) (1) upgrade the project (2) immediately rename the "themes" folder to "themes_2" and then find the Atlas 3 theme (it's a downloadable zip) and drop in there as the new "themes" folder. Then I upgraded my deeplink and community commons modules (just redownloaded and replaced). Then downloaded Atlas Core and the Atlas Web Components/Resources... After that it seemed to work. If datagrid2's or any other CSS is wacked out after an upgrade, it's likely something was just done out of order.