FTB (New Source) disrespects release stream selection, shows arbitrary version numbers

OS Name/Version:
Ubuntu 22.04 LTS

Product Name/Version: (Always use the full version number - not ‘Latest’)
AMP Release “Triton” v2.3.4

Problem Description:
The pack selector does not care about the release stream selected and also seems to show arbitrary version numbers.

Steps to reproduce:

  • Create new Java Minecraft instance
  • Select “Feed The Beast (New Source)” as server type
  • Select e.g. “FTB Presents Direwolf20 1.18” as FTB modpack
  • Note how either version 1.4.1 or 1.5.1 is shown, regardless of the release stream selected
    (Installation seems to consistently be version 1.5.1, the currently latest stable release, 1.6.1 is latest beta release but neither shows up nor gets installed with selection “beta” or “development” as release stream)

Actions taken to resolve so far:

  • change release stream (+ browser refresh)
  • restart instance (+ browser refresh)
  • restart complete AMP system (+ browser refresh)
  • restart OS of AMP server (+ browser refresh)