Thanks, the screenshot has a clue! For some reason, Whisperfish can’t load the image properly, and fails to (well, stays at really) the blurhash thumbnail of the image.
Also “it works in beta.19 but not in beta.20” is an important detail here (and it helps hunting down the issue).
Could you please create an issue for this in Gitlab, and attach the screenshot there? Any chance you could attach terminal logs there (don’t forget to sanitize them first)?