I’ve just noticed that my metrics formulas are being updated across ALL glyph masters in the occasional (non-component) glyph.
ie. in light x glyph the LSB is n-5 and any update to that has changed the LSB in regular and bold to the exact same formula as opposed to n-3 or whatever individual values.
from time to time I select all and update metrics.
It looks like - on deadline - all the careful tweaking I’ve done has been decimated.