OK, I got this to work but you probably won't like how I had to do it. Before we get to how it worked, let me outline a few things that did not work for me.
- Replacing the labels of an option set with the integer values with an excel import
- Replacing the labels with integers, and replacing the semi-colon with a comma with an excel import
- Removing extra spaces with both of the above formats with an excel import
- Trying the new Preview import feature from directly on the table in make.powerapps.com
- Cursing quietly at my computer screen and threatening it until it imported properly
- A few more random formatting things
In the end, I could not get it to work through the excel import no matter what I tried. Unless I'm missing something, that's a dead end.
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So, I decided to move over to Power Automate to see what I could do there and if I could update a Multi-Select field. The answer is YES, but the formatting is wonky. After a bunch of errors, I decided to just do a "Get a Row" action so I could see how multi-select fields were being stored and referenced in a flow.
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As you can see in the screenshot, it was storing it with the option set values separate by a comma. I tried putting that directly into a step to update this field in another record, like so.
This did not work, and I got the error that the values being passed in were not integers. Passing them in with quotes around obviously didn't work either.
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I finally was able to make it work by using the formula input to convert both fields to integers and separating them with a comma. You basically need to force the field to accept both the option set values as integers but still include the comma separating each value.
This ran successfully for me, and it added both choices to my option set. Hopefully this gets you far enough along that you can write a flow that reads your updated excel file, build out the update value as needed based on the selected values, and updates it according to this format. Unless or until someone comes along who knows a different and hopefully easier way to do it, I can confirm that this at least worked for me.
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Good luck and let me know if this works out or you find an easier way.
