They works in foot but not in head.

'tick' still works but it seems 'every' doesn't. comment it out and ticks appear again

Problem crept in due to the update from var to let for render-marks.js

Line 34 declares offset as const in local scope of the code segment that handles tick / tock value being a single number, but offset is a 'let' variable that is supposed to be available everywhere in the function.

Line 34 of https://github.com/wavedrom/wavedrom/blob/trunk/lib/render-marks.js

cc @drom

Just removing the 'const ' from the line fixed the problem.