Conversion failed when converting from a character string to uniqueidentifier

Same error, except now I get it in query editor and not when refreshing the table in Power BI:

DataSource.Error: Microsoft SQL: Conversion failed when converting from a character string to uniqueidentifier.
Details:
DataSourceKind=SQL
DataSourcePath=prod-sql.database.windows.net;prod-db
Message=Conversion failed when converting from a character string to uniqueidentifier.
Number=8169
Class=16

let
Source = Sql.Databases("prod-sql.database.windows.net"),
#"prod-db" = Source{[Name="prod-db"]}[Data],
dbo_vps_Sum = #"prod-db"{[Schema="dbo",Item="vps_Sum"]}[Data],
vps_Buffer = Table.Buffer(dbo_vps_Sum)
in
vps_Buffer

I tried deleting the relationship between this table and another but that didn't help either.