Strange A# data type - No enum constant

I have a Dremio dataset pointing to a MongoDB collection.
The collection has column called date which was initially an ISO-formatted string in MongoDB.
I have now converted it into MondoDB date type directly in MongoDB. Dremio now shows type of this column in the dataset as yellow letters A#. When clicking on it (trying to change the type), I get the following error:

No enum constant com.dremio.common.types.TypeProtos.MinorType.DATEMILLI

What am I doing wrong? How can this be fixed? The goal is to make Dremio treat this column as date type for future joining and filtering.

Dremio build: 2.0.1-201804132205050000-10b1de0

This may be a bug and we can try to reproduce here. Meanwhile, I wonder if refreshing the metadata will get you past this issue:

Note this command has some side effects you should consider related to reflections and security.

Normally Dremio will automatically adjust to changes in schema through it’s schema learning engine. You may be able to trigger this by running a select * on that collection using Run (with a limit if you need to).

Run did not fix it, unfortunately.
I found in Dremio documentation that A# denotes a mixed type (it would be great to have it in the table listing all type symbols). But my date column is not mixed (had strings in all rows, now dates). And Dremio does not allow me to change the type.

From this tutorial, see the section on mixed types:

You could try working through that wizard. Alternately, maybe some of your records are still strings?

Did you try refreshing the metadata?