Issue is that Harmony is calling the command on the A20 Pause button PLAY and using that as the sole Play/Pause function. The command on the A20 Play button is apparently missing from Harmony. So you may have to try a few different model choices in the Harmony database until you find a set of commands with distinct play and pause functions. Then you need to assign each to distinct buttons on your Harmony.
Alternatively, there may be another command that accomplishes the same thing, like OK possibly.
Alternatively, there may be another command that accomplishes the same thing, like OK possibly.