Happens also with only 1 datetime column in the table. Seems to be an issue with specific data in the table or column. For a different table with a datetime column it displays the data.
Just found out that for the table with one datetime column (NOT NULL) it was because of the default value of "0001-01-01 00:00:00" in one row. I added the column later after creating the table.
For the table with 2 datetime columns i guess it may be because of NULLs in one column?
I installed v5.0 because i wanted to see if the refresh button works better now in the database explorer (it only refreshes right/data side if the focus is on the left/table side) but it works as poor as before with v4.6...