The filter options for spells currently allow you to filter by the 5 colours, and a 6th option for “no element”. This appears to be a copy of the sort and filter options from equipment, and while it makes sense for equipment to have items without colour, it doesn’t make sense for spells since every spell has a colour.
I would suggest replacing the “no element” filter option with “filter on current class”.
That could either:
Filter to show only spells specific to current class.
Filter to show only spells that can be equipped by the current class.