It is a wonderful thing when PowerApps works as intended, and we’re all able to make and use awesome apps quickly and easily! Although this occurs most of the time, we know how frustrating it can be when you’re bottlenecked due to lack of information, product issues, and/or unclear error messages.
PowerApps currently doesn’t support out of the box multi-valued fields – columns in a data source that can take zero or more of a predefined set of values.