I am selecting the files within the folder and adding all selected files to to now playing in MMA.

I just tried this same operation on an S5 running android 6.0.1 and MMA 1.3.2.0822 and it behaved the same way. This began immediately after updating to the latest MMA on the S2, so i suspected MMA 1.3.2.0824, but there must be something else going on in my system.

Are you saying you're selecting the Album folder for Playback and not the Files within the Album folder and in that scenario only a single file gets added to the Now Playing in MMA?

After updating to MMA 1.3.2.0824 adding an entire album of songs to the Now Playing list via UPNP > location (my preferred method) results in only one song being added. If I navigate through album rather than location all selected songs are added. I have tested this on a pixel 2 running android 9 and on a galaxy s2 running android 4.1.2. Both devices behave the same. I also tested connecting to both the MMW server (my normal routine) and also to the NAS media server. Results were the same with both servers.