When viewing my collection sets at either:
&
I noticed that I was only able to see or interact with the 1st Series cars, with the end of the domain being:
0-0 = common
0-1 = rare
0-2 = premium
0-3 = NFTH
There is no way to toggle or click into the other Series, so I tried modifying this ending to 1-0, 2-0, 2-2, etc. and the first digit quickly reverts to 0 and the Series 1 collection is displayed.