Block-sparse attention tiles the latent into (4, 4, 4) chunks and asserts every
axis divides evenly, so a side must be a multiple of 64 -- the VAE's 16px cell
times 4. At height 480 the preset turned the flag on and the pass silently fell
back to DENSE attention, which at ~37k tokens is both much slower and what ran
a 24GB card out of memory on the first continuation segment of a 304-frame
clip. 832 already divides by 64; 512 is the nearest height that does.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>