Crashes part way through encoding with gtk errors

[taprobane99]

system: flatpak, latest version, gnome 48, kernel 6.14, wayland, vulkan, raspberry pi 5 4 gb.

starts encoding then this repeated twice around 4% and 5%

(aviator:2): Gtk-WARNING **: 18:03:28.862: Trying to snapshot GtkGizmo
0xaaab773730d0 without a current allocation

then around 13%

Gtk:ERROR:../gtk/gtkwidget.c:3909:gtk_widget_ensure_allocate_on_children:
assertion failed: (!priv->resize_needed)
Bail out! Gtk:ERROR:../gtk/gtkwidget.c:3909:gtk_widget_ensure_allocate_on_children:
assertion failed: (!priv->resize_needed)

and the whole app crashes.

(I ran Aviator from the terminal to get those messages)