Power Query SharePoint List Error with Allow Multiple Selection on People or Group Field

I was getting a similar error:

DataSource.Error: We couldn't parse OData response result. Error: A null value was found for the property named 'AssignedToId', which has the expected type 'Collection(Edm.String)[Nullable=False]'. The expected type 'Collection(Edm.String)[Nullable=False]' does not allow null values.

I have "Assigned To" column in my list, and I changed it to not allow multiple selections. So now I am getting this error:

DataSource.Error: We couldn't parse OData response result. Error: A null value was found for the property named 'PreviouslyAssignedToStringId', which has the expected type 'Collection(Edm.String)[Nullable=False]'. The expected type 'Collection(Edm.String)[Nullable=False]' does not allow null values.

I don't even have "Previously Assigned To" column in my list, so where is it coming from?

If I change the API version from 15 to 14, I get an error as the poster above:

Expression.Error: The key didn't match any rows in the table.
Details:
    Key=Record
    Table=Table

Is there some kind of work-around for this issue?