Subtitles not working since 0.13.17 update (incl. all current versions, .18-.19)

*I'm submitting a ...*
- [x] bug report
- [ ] feature request
- [ ] support request

## General infomration

Subtitles do no longer work, i.e., by being available, in the most recent versions 0.13.17 and 0.13.18.

### Prerequisites

* [x] Are you running the latest version?

### Description

I upgraded to 0.13.17 (from an unknown version number) after Netflix videos stopped working, which is probably related to the VP9 issue that was addressed in the most recent updates. However, as at least one other person noted in comments, subtitles stopped working for me. The "T" key no longer activates subtitles which were available in the past, nor does the subtitle menu offer any pre-loaded language options.

After updating to 0.13.18, the issue remains.

### Steps to Reproduce

I can confirm the issue arises with Narcos, Season 3, Episode 1, which I have watched with subtitles before, simply by activating using the "T" key.

## Context (Environment)

I am using LibreELEC, Milhouse build: devel-20181006210251-#1006-g24504bb , with KODI 18.0 Beta 4 running on RPi2.

### Installation

* [ ] I installed the plugin via zip from the Releases page
* [x] I´m using the Netflix Repo
* [ ] I´m using a different source (Please tell which)

### Operating System

* [ ] Linux (x86/x64)
* [ ] OSX (x86/x64)
* [ ] Windows (x86/x64)
* [x] Linux (ARM) =
* [ ] Android

Reproduce the problem with Narcos, Season 3, Episode 1 on Kodi 18.0 Beta 4 running on LibreELEC ARM with the Netflix Repo, testing both the T key and subtitle menu. Compare behavior with versions 0.13.17 through 0.13.19; done means previously available subtitle languages appear and can be activated.

Written by the indexing model from the issue text.