Your problem is the "switchbacks" that you created from the right page to the left. You can't do that. Linking the left page to the right and leave it at that should do what you want, though you may have to delete the master frames, or apply a page without them, on any pages you don't want your threaded text.
It looks like you are trying to do a 4-up imposition? Is this something you are printing in house? Most printers would be able to do the imposition for you from a document setup to the flash card's trim.
If you uncheck Allow Document Pages to Shuffle you can start the document with a facing spread:
Delete page 1 and you'll get this:
As Peter suggests you could start the thread on the left, but you will still need to start with a facing spread:
It doesn't really matter if you start with a right or left page in the document (at least as far as ID is concerned about threading). New pages should be added automatically.
I may be misunderstanding the question but looks like an attempt to handle imposition in the layout.
When I start the doc with page 1 on the right I don't get the correct threading. Frame 1 threads to frame 3 and not the desired 2 frame, which is on the left page of the following spread (In my captures the numbers are labels and are not in the text flow)
When the first page is part of a facing spread I get the correct threading—text frame 1 threads to text frame 2 on the left page of the spread etc:
And an auto flow works with 8 going over to the next spread's 1:
You're probably correct on this -- I didn't do any testing, and I probably would find a different method of getting the text into this -- possibly not back-threading at all, but have 4 independent threads, then preset the number of pages and flow the first group, pick up the overset and flow into the second group, and so forth..