SOLVED: Gentoo: This file does not support seeking and cannot be used for editing

shotcut-25.08.16 on Gentoo. Trying to add static images (png, jpg) to playlist, popup appeared:

This file does not support seeking and cannot be used for editing.

jpgs would appear as empty (solid white) squares; pngs would have a thumbnail but could not be added to a timeline.

SOLUTION: re-emerge mlt. Here, if it helps, is my mlt and its USE flags

[I] media-libs/mlt
     Available versions:  7.38.0(0/7)^t ~7.40.0(0/7)^t {debug ffmpeg frei0r gtk jack libsamplerate opencv opengl python qt6 rnnoise rtaudio rubberband sdl sox test vdpau vidstab vorbis xine xml PYTHON_SINGLE_TARGET="python3_12 python3_13 python3_14 python3_15"}
     Installed versions:  7.38.0(0/7)^t(04:56:29 PM 09/17/2026)(ffmpeg frei0r gtk jack libsamplerate opencv opengl sdl sox vorbis xml -debug -python -qt6 -rtaudio -rubberband -test -vdpau -vidstab -xine PYTHON_SINGLE_TARGET="python3_14 -python3_12 -python3_13 -python3_15")
     Homepage:            https://www.mltframework.org/
     Description:         Open source multimedia framework for television broadcasting

This is not a shotcut bug, but it cost me three hours and I’m hoping that by posting here (and immediately closing, if I’m able) someone else may save that time.