I'm not sure what is meant by a "checklist" vs checkboxes for the online version, I only see it on the app (I don't like the strikeout feature which is why I never considered using that). The checkboxes should work without sometimes reformatting to bulleted lists between platforms and then "saving" that way. In the online ribbon, I don't see any option for checklists, just the option to create a checkbox, bulleted list, or a numbered list. I just want a checkbox, then some text (such as a "buy list" of items), and then I can check it and uncheck it depending on whether I currently determine I need to purchase that item again, without any strikeout reformatting.
Besides turning a checkbox list into bulleted lists uncommanded, random line-spacing is often added between platforms, such as between the online version and Android. It seems to be a system compatibility issue, maybe related also to the presence of hidden formatting elements embedded in the note. Cross-platform functionality is one of the primary reasons I otherwise find Evernote useful, and I think that should be a core focus of Evernote staff. I hesitate to expand its use into my work/ business and continue to use other systems for those as they are more critical to have error-free productivity. I spend a lot of time fixing auto-reformatting bugs in many of my notes when I switch platforms. Lately, upon opening a note, it often starts at the bottom of the note, and I have to then scroll back up manually to the top (Android app). Numerous formatting and other bugs like these are pretty common, having used Evernote for many years now. There are many ways to use Evernote, and they should all work; having certain ways of using it remain buggy but available is weird to me.