Application (Chrome) ends up without icon

[ALinuxUser]

I have a script that, whether launched from an icon on the desktop or from a launcher in plank, ends up with no icon at all - just a floating running indicating hovering below emptiness, as in the image attached to this report.

The script runs a 'Chrome app', waits for the app to end, does some stuff, and then itself quits.

The script is here: https://pastebin.com/iPnB45sV.

System information:

MMMMMMMMMMMMMMMMMMMMMMMMMmds+.
MMm----::-://////////////oymNMd+` ---------------
MMd /++ -sNMd: OS: Linux Mint 18.3 Sylvia x86_64
MMNso/` dMM `.::-. .-::.` .hMN: Kernel: 4.14.7-041407-generic
ddddMMh dMM :hNMNMNhNMNMNh: `NMm Uptime: 6 hours, 23 minutes
    NMm dMM .NMN/-+MMM+-/NMN` dMM Packages: 3802
    NMm dMM -MMm `MMM dMM. dMM Shell: /bin/bash
    NMm dMM -MMm `MMM dMM. dMM Resolution: 1280x800
    NMm dMM .mmd `mmm yMM. dMM DE: Cinnamon 3.6.6
    NMm dMM` ..` ... ydm. dMM WM: Mutter (Muffin)
    hMM- +MMd/-------...-:sdds dMM WM Theme: Linux Mint (SimpleX-Grayscale_custom)
    -NMm- :hNMNNNmdddddddddy/` dMM Theme: Mint-Y [GTK2/3]
     -dMNs-``-::::-------.`` dMM Icons: Paper [GTK2/3]
      `/dMNmy+/:-------------:/yMMM Font: Noto Sans UI 11 [GTK2/3]
         ./ydNMMMMMMMMMMMMMMMMMMMMM CPU: Intel 2 Duo T7500 (2) @ 2.201GHz
            .MMMMMMMMMMMMMMMMMMM GPU: Intel 965GM
                                     Memory: 2139MiB / 7970MiB

Plank version: 0.11.4.13-c845 Development