Losing Pop-Up Menu When Adding Subtitle to Multi Episode Blu-ray

[maczones]

Pilling my hair on this one. Here's the problem: I have a BD with 4 episodes with a working pop-up menu on demand. Each episode has one NL subtitle available and I want to exchange that subtitle file with an English .srt sub. Using tsMuxeR, I load up the first episode, remove the NL sub and add the English sub and remux. After exchanging the m2ts, mpls and clpi files, I replay the BD but the pop-up menu now does not appear. Not sure what has changed in the replacement mpls or clpi files to make it act this way. Is there something I need to do in BDedit to fix this or is there something else to do?

TIA
Maczones