Pavlovia Survey: flow blocks keep disappearing but leave artifacts

I’ve created a new pavlovia survey and I’m trying to set the “flow” using multiple blocks. I changed the name of the blocks and then added test questions. First the survey pilot could not go from one block to the other, and instead just completed the survey after the first block. Then, blocks disappeared, and when I tried to create new ones and rename them, I would get a warning that the name is not unique.

Looking at the survey model JSON, I can see that most of the blocks I’ve created are there, but the data makes little sense when comparing to what I see in the preview and flow screen. The “surveyflow” tree seems to suggest I have only two main blocks when I have three, and the middle shuffle block has four nodes visible in the flow but on the JSON it does not refer to the same blocks visible in the builder.

I am at a loss as to what to do, currently I’m trying to manually edit the survey model and import it as a new survey…