Hi,
This is described in the DFFS change log: https://spjsblog.com/dffs/dffs-change-log/
Cascading dropdowns v3.527 (December 14, 2015)
Fixed a bug where the next dropdown was hidden if the query did not return any items despite the setting “Hide the dropdowns when they have no available options” being unchecked.
Added a check to flag “dirty” data where the string contains two or more consecutive spaces. Due to a bug(?) in Internet Explorer 8 (and possibly 9 and 10) that collapses these into one single space. This behavior causes the query for the next level to fail as the query specifies a single space value while the actual data stored in the db has multiple consecutive spaces.
This is a problem that is hard to fix in the script because SharePoint will strip these double whitespace out when returning the items from a query (look at the item in DispForm and you will see only one whitespace).
The cascading dropdown script will therefore not “see” the the double whitespace. When it then asks for matches to the next query, the result is no matching items because it has a single whitespace string in the query and the db has double (or more) whitespace in the string.
I’m afraid the only solution i know of is to “wash” the records in the lookup list.
You might find the affected items easier by using Google Chrome and search for ” ” (two whitespace characters) in a list view.
Alexander