Entities do not appear in Dataflow when creating Linked Entities

I am having a similar issue, I could not create a new linked entity from a new dataflows Entity (which I created today).  I also lost an existing entity link.   It was a date table, however when i tried to load the dataflow containing a group of linked entities it throws an error complaining the original entity wasn't valid.

The best I can tell is Entity with a Date in it, will not longer appear for selection when linking.  The workaround suggested didn't help me.  I have 2 workspaces, one containing fact/dimension dataflows and anything will a date is problematic. I can see Dates are being stored as "Unclassified" for the data type.  To expand a little:

Workspace 1:  has 2 dataflows for building the entities.  Any field that contains a date field are now unclassified.

Workspace 2:  has 2 dataflows that link the entities from Workspace one.  I cannot see any Entities from Workspace 1 that contain a Date field.

When i try to link from workspace 1 to workspace 1 (just a test i wouldn't actually do that in the real world), I cannot see any Entities that contain a Date Field.  The new entity i created  cannot be linked and doesn't appear either and it contains no dates.

Last week I was having a problem with Date fields where being stored as DateTime (despite selecting "Date" as the type).  I am not sure if they have attempted to fix that, but this is a pretty big regression.  Essentially dataflows are now unusable. 

It is pretty bad if it is going to take 5 days.  I cannot raise a support ticket as I don't have the privileges to do it (my company has strict controls).  I would be interested if anyone else has these symptoms.