For anyone experiencing the issue with the white text box seeming to appear off screen or be missing, I found a fix in the xml files for the mod and you can follow the steps below.
1. Open the data > themes > android folder in your "PokeMMO" installation directory
2. Open android.xml with Notepad (or your preferred notepad equivalent)
3. Click Edit > Find (or Ctrl+F on your keyboard) to bring up the Find box
4. Type in "npc-interaction-popup", make sure the "Direction" is set to "Down", and click "Find Next"
5. You will be taken to a section with the following text:
<theme name="npc-interaction-popup" ref="-defaults" allowWildcard="true">
<param name="background"><image>mobile.bubble.background</image></param>
<param name="border"><border>30,30</border></param>
<theme name="labelanimation" ref="label" allowWildcard="true">
<param name="font"><font>med-noshadow-22-gray</font></param>
</theme>
6. In the second line, replace "mobile.bubble.background" with "text-bubble.background"
7. Click File > Save
8. Launch the game, and enjoy
