See image below. When I generate a simple reading plan, it automatically generates additional blank lines.
I can confirm this by following your screenshot. I have never created a reading plan "at your own pace." If you create a reading plan by chapter, every day, 31 sessions, it will work better.
Actually, I just modified the reading plan I suggested to go back to what you have and it works:
So it does appear that there is a bug, but you can get around it.
When I generate a simple reading plan, it automatically generates additional blank lines.
Blank lines which act like Readings, as the Plan won't advance to the next chapter until you have manually marked the intervening steps as Read.
Also, the Reading Plans Visual filter is not immediately populated when clicked. This specific Plan showed after 3 attempts to activate it.
Bug confirmed for Logos 9.11 SR-1.
I've created a case for this bug.
I recommend JT's workaround.