'xp add @p 0' acts weird when player is not fully loaded

With my simple command block contraption in this brand new world, we can see that when the redstone signal from the repeating 'xp add @p 0' command block turn off, and powers the 'say no' command block, otherwise the 'say yes' command block is on. When looking at the log(chat fills up too fast), we normally see the a spam of 'yes'es, but upon logging in, we get a spam of both 'yes'es and 'no's.