Sourdough starter stopped growing, is it normal? I posted a question a few days ago. This was my first sourdough starter: My sourdough starter split in 2 on the 3rd day. What should I do?

and I decided to only keep the foamy part and throw the other half away. After another day that sourdough stopped growing and became kinda liquidy and I threw it away and started another batch.

2 days after and I am in the same situation. My sourdough starter split in two, exactly the same as in the above link. But this time I decided to simply stir it and feed it as usual.

After the 2nd feed, the starter kept splitting in two and the foamy part started to get smaller and smaller. The bottom part stopped making bubbles and simply stayed the same way.

6-7 hours before the 3rd feed the starter looks like the below picture. It stopped growing and it seems that only the top layer has bubbles. Is this normal? 

It is also weird that two different starters have the same exact evolution, maybe there's something wrong with the flour?




EDIT:
So after 7 more days of feeding and three attempts here is my latest result:


Thank you for your advice!
Nothing that happens in a starter in the first few days is normal, in the sense that it doesn't behave like a mature starter. During this time, the bacterial flora in the starter is in constant flux, and you need to wait until the desired bacteria have prevailed, which will take some time. 

It is not impossible to do something wrong, but you will only know it when the starter has stabilized, or rather failed to. Until then, just keep the regime exactly as prescribed, no matter what visible changes happen.