IPTVnator resolving (choosing) low resolution rather than high resolution

[what-a]

For some sub-playlists (i.e. a playlist stream embedded within a playlist typically ending with "index.m3u8") IPTVnator is staying on low resolution rather than switching to high resolution (even when there is plenty of internet bandwidth).

For example, load the playlist below and then view channel WPBT:
https://raw.githubusercontent.com/matthuisman/i.mjh.nz/master/PBS/all.m3u8

Testing channel WPBT in both VLC and IPTVnator shows:
VLC starts on a low resolution stream but quickly resolves to a 1080p stream.
IPTVnator stays on a low resolution stream and never (or only briefly) increases to 1080p despite plenty of internet bandwidth. 😟

BTW, the sub-playlist for the WPBT stream within that playlist is;
https://wpbtdt.lls.pbs.org/out/v1/0fbd3da6bffb465ba84f94abaff14973/index.m3u8

Based upon bandwidth, an "index.m3u8" sub-playlist should allow IPTVnator the flexibility to choose resolutions. For the WPBT example the choices are;
1080p
https://wpbtdt.lls.pbs.org/out/v1/0fbd3da6bffb465ba84f94abaff14973/index_1.m3u8
720p
https://wpbtdt.lls.pbs.org/out/v1/0fbd3da6bffb465ba84f94abaff14973/index_2.m3u8
432p
https://wpbtdt.lls.pbs.org/out/v1/0fbd3da6bffb465ba84f94abaff14973/index_3.m3u8
234p
https://wpbtdt.lls.pbs.org/out/v1/0fbd3da6bffb465ba84f94abaff14973/index_4.m3u8