The flowchart and flowchart-vertical blocks read tl.labels["hold5"] back
from the timeline to schedule the "Pythom" -> "Python" typing correction.
The render compiler executes composition scripts under a GSAP proxy whose
timeline exposes no readable .labels map, so this line throws
("Composition script failed ... Cannot read properties of undefined
(reading 'hold5')") before window.__timelines is assigned. The block is
never registered: renders show only the dotted-grid background and every
render pays the 45s sub_timeline_readiness_timeout.
Use GSAP's own label-relative position syntax ("hold5+=<offset>") instead,
matching every other step in these files. Identical timing, no .labels read.
Verified with hyperframes@0.7.60 render: block was blank before, animates
after; the readiness timeout disappears.
Paweł
b44bc4ffaf