Currently, I'm working on an EB that had its maps (3 pages total) working during development. However, the maps quite loading at some point (during the addition of multiple views for widgets and associated buttons). I did have a span of time where all the created widgets worked just fine. Then, the maps stopped loading on each page. Naturally, I go to re-add them and when I do I receive a red "i" and the "No added data can be used. Please add data." errors. The red "i" on the left simply reads as "Error" on a hover. One ESRI community solution mentioned updating layers in the maps that were not working (there is one in one map I'm trying to use). However, I open a blank EB and add the same map to it and the map loads just fine.
So, I'm at a loss and hoping the community can point me in the right direction!