MKV/MP4: Issues with Chapters

I have an LG BP200 in my living room. I'm happy with this player except for one very frustrating issue. Whenever I want to watch an MKV/MP4 file, whether I plug a hard drive in the USB or whether I have it on a data disc, I cannot skip forward to the next chapter in the file, it jumps straight to the next file on the drive/disc. However, skipping back to the previous chapter works. My issue is with skipping forward.

I mux the chapter file with MKVMergeGUI and I know for a fact they work because I have a TOSHIBA Blu-Ray player in my bedroom that recognizes the chapters and allows me to skip back and forward at my leisure. But with the very same MKV/MP4 files in my LG BP200, bupkus.

I've tried both .txt and .xml formats, tried manually encoding them to UTF-8, even UTF-16. But nothing seems to solve my problem.

It's not the skip forward button that isn't working because if I watch a DVD or Blu-Ray movie, the skip to next chapter works.

Furthermore, there's an Info/Menu button on the remote that lets me view the info of each file. If I'm watching the third file out of ten I have on my drive/disc, the "Title line" will display 3/10. Beneath that line is the "Chapter line," which displays which chapter in the file I'm on out of the total available in each respective MKV/MP4 file. (Example - on the right side below "Displaying content information on-screen") Again, while I watch DVD and Blu-Ray movies, the "Chapter line" is displayed and I can skip straight to my desired chapter. Problem is that with my MKV/MP4 files, the "Chapter line" is not displayed.

If anyone has any info to give me, I'm more than all ears.
Thanks