Here is what I would try.
1. Go to your Apps Tab
2. Select the ... from your Apps Line, select Details
3. Go to the Version Tab
4. Do a snap shot picture / screen shot
5. Restore the previous version just before the published. Make sure no one is trying to have it opened at all.
6. CTRL F5 your browser when it says its done
7. Try to edit the app again
Hmmm the font is small I missed it
Do you mean you did the above steps already
i published a previous version of the canvas app. From the home page of this canvas app, i can select Manage Master Tables and the form loads. When selecting TRANSACTIONS, nothing happens. See attached.
Can you paste in pictures instead.
Also, try to publish all customizations
then export your solution (into an unmanaged solution)
then try to open it again