subtitle Command Working Inconsistently

I just joined the world.
There are 2 command blocks, one is for title, one is for subtitle. They are connected properly.
When I press a button to activate the first one, only the title apppears. If I do it again, both the title and the subtitle appears.
There is another set of command blocks, same thing but different text. When I send a redstone signal to them, the title is correct but the subtitle is of the previous set of command blocks. When I do it again, it is now displaying the correct subtitle.

This bug is very annoying for map makers.
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