Recording keys under function key in macros

Hello,
I have an issue with recording macros in Synapse 3. Function key does nothing while recording macros. I don't mean that it is not recorded as a separate button but that it doesn't modify other keys. For example if I stroke 'J' with 'Fn' button pushed down, it is recorded as 'J' despite the fact that outside recording macros "Fn+J' is an arrow left (Huntsman Mini). Since this keyboard doesn't have arrow keys, using "Fn+' is the only way to record them. I hope I described my problem in a comprehensible way xD