Joins using the GlobalID of one dataset and the globally unique identifier (GUID) of another dataset are not possible in ArcGIS Online, but are possible in ArcMap.
Duplicate of BUG-000119301. This issue is addressed in ArcGIS Enterprise 10.7 and ArcGIS Online 7.1. There is a hot fix created for this issue in ArcGIS Online 10.6.1.