The 400’s are Queen first card pairs and 800’s are Jack first card pairs. Remember that if a face card is 1st or both cards are face cards, then it supersede’s the suit combination.
For Example:
Q
2
= 492
J2 = 892
QQ = 449
JJ = 889
QJ = 489.
JQ = 849
This is why 444,448,484,488,844,848,884,888 can’t be generated in this system. There are no suit pairs that spell out R (4) or F/V (8).
The rules are WAY different when it is JUST a Jack 2nd or Queen 2nd and a # card 1st, so I suggest you reread that part again.