TLDR Summary -
Note that this is using methods described in the forums and blogs on how to do this (ie: such as editing themes) that worked in the past.
All of these issues were encountered by trying to resolve another bug whether PowerApps got an app into a state where it would NOT load outside of the dev environment. After hours of debugging and comparing a working version and the none working (that had additional code I needed and would have taken a while to merge back into the working one), discovered there were some small issues that PowerApps created in the 1.json file for the App control (3 minor parameters).
Attempts at the above were to resolve that, but I kept running into problems. Note that the problems above with export and import exist with other (simpler) apps.
PowerApps Studio 3.19062.18
Happens with Google Chrome (latest 64 bit), latest (as of yesterday) stable Chromium 64 bit build (with no extensions, etc, default settings), and MS Edge.
How do you export and import your App?
Do you test with other environments and is there also the same issue?
I test on my side export and save on loacal and then import and there is no the issue.
So could you please change one environmnet to test?
I've tried exporting by BOTH doing Save As (This computer - to a local file) from within Studio - which directly exports the MSAPP, as well as clicking on the ... from the app list screen and selecting "Export package (preview)" which instead exports the whole thing to a ZIP file (ie: manifest.json, as well as directories for included PowerApps, MSFlow, etc, with the MSAPP further below).
And then trying to import the MSAPP directly with Load (Browse Files) to load from the local computer, as well as from the app list screen with "Import package (preview)" to load the ZIP file.
As mentioned in the other thread created by @JamesA (https://powerusers.microsoft.com/t5/Administering-PowerApps/Injecting-updated-JSON-into-msapp-withou...) after I posted this one (seems we both saw these issues at the same time, so most likely this is a recent thing - I know this did work properly 2 months ago).
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