I noticed if I choose chain first (less likely to start this way), then click elements, I get my 0.3 defaults, if I click an element first (more typical) and then enter the chain via the settings cog, they are 0
What's also missing is an "external"/"global" start/end that we can use to move all elements in that list at once. Is it the end of the world to adjust each entry in the list individually? No, I'm not that dramatic, it is still lengthening the workflow to have to go through them one by one and only because they didn't apply the defaults I am most likely to use.
I hope the note on where it does and does not apply the set defaults helps you pinpoint why we don't get defaults where we should also get them.
A simple pop up asking if we want to apply the global settings (were they to be added to the dialog) to all elements would ensure there is no issue with losing custom start/end extension values (I'm sure the pop up could even include that values were customized)