Motion scroll effects for masking

[lj_bl]

Hi, is it possible to use muse motion scroll effects for masking? In the below example I'm trying to use white blocks to reveal the back line as if its being drawn.

I cant seem to get everything to align though.

see attached muse file: https://nofile.io/f/PF2m2rG6581/muse+mask+test.muse

[Preran]

Not the exact answer to your question, but sharing an article that provides insights (in case you did not read this article already).

Design ideas to use Scroll Effects in Adobe Muse