Excel add-in running on shared runtime randomely stops reacting to buttons in Excel Online

[taralex77]

A published add-in that works great in the desktop versions of Excel in some documents stops reacting to button presses in the ribbon (the task pane just doesn't open).
We added some logs and it appears that the script entry point doesn't even get hit, so the plug-in is not initialized, even though it shows up in the ribbon correctly. This is completely random, in some documents it works fine, but in some – it doesn't and no amout of reloading of the page helps. This is causing major issues with the users, has anyone seen such behavior?

[RuizhiSunMS]

Hi @taralex77, thx for reaching out here.
As far as I know, no similar issues so far. Suppose lack of necessary information, would you please share more?

1. what addin?
2. your office version
3. have you ever met it on Excel Web?
4. a stable repro guide

[taralex77]

This is the plug-in: https://appsource.microsoft.com/en-us/product/office/WA104382023?src=office&tab=Overview
It only happens in Excel Onine, so I guess office version is irrelevant.
Reproducing is super hard, I was able to when opening all my documents one by one until I stumble on one where it doesn't load.

To add a little details to the issue description, we tracked what happens during the load:
When the document is loaded, the ribbon bar tab appears correctly, then all icons for the buttons are loaded as well as function.json. And that's where it stops, none of the rest of the files (html and js) are loaded.
Do you have any tips on how to better debug such issues? Is there some sequence of things that should be loaded so that we could track them one by one to understand where it when it fails?

[RuizhiSunMS]

@taralex77, I just realized that you submitted another case for this addin on another problem?
Back to this case, I did a try and it works well. Would you please confirm something?

1. is it stable to repro on one of your file?
2. does anyone else can repro this with your file?
3. can any other files be used in reproducing?
4. have you ever tried f12 or fiddler to check whether html, js or other files get loaded or not?

[taralex77]

Hi Ruizhi,

Thank you for bearing with me!

1. This is the challenging part. While it's reproducable on our end (only for one of the users) – it may work perfectly file in the same file for a different user when shared. Or it may not work, and then magically start working for everyone in a couple of hours or days. I had one such file, but it started working as soon as I shared it with the dev team. It's not of much help for our customers though as they get extremely frustrated that some files just stop working for them randomely.
2. At one point there was a file that didn't work for me, I shared it with the dev team and it didn't work for them for about a day. Then it started working for everyone. During that time they were able to record the Network traffic and Console and what they found is when the user clicks on the "Show Sidebar" button – nothing happens, because the plug-in code is not loaded. In the Netword tab we can see that only the icons for the ribbon buttons and "function.json" file get loaded.
3. Completely randomely. I can go through tens of files in my OneDrive and find one, we would use it for debugging for some time, but then it would start working completely randomely. We do have an exported ".har" file (network activity) for the file that wasn't working at the time of testing.
4. Yes, as described above, it never comes to loading the HTML when the user clicks on "Open sidebar" or any other button. It only loads ribbon button images and "function.js". We do use a function to open the sidebar since we're using shared runtime, should we use a link instead?