(EE 2.9.2, Low Vars 2.5.0, and Content Elements 1.7.0)
I've created a variable in Low Vars (LV) and made it a Content Elements (CE) type. By default (and understandably yet still annoyingly, I might add), CE displays all possible field types it can handle in new variables: Code, Gallery, Heading, Rich Text, etc. So I go about the usual routine of deleting them all to clear the board for my own custom-named fields, including things like "Image (full width)", "Image (on left)", "Image (on right)", etc.
I then click on the "Save Changes" button, and it loads up the screen where I can begin to add the different CE types as I please and populate them with content... except after all the custom fields I created, I see all the default fields as if they had never been deleted... O.o
Going back in to the CE var's settings, I do indeed see my fields followed by all the default fields. Leaving things as-is and clicking "Save Changes" results in 3 sets of fields to select from - my custom ones, and then 2 sets of the default CE fields. o.O
So each time I save the CE variable, it re-adds the default set of fields. :-/
I might add that the process of saving changes and/or loading the page after that takes an inordinately long time - 45-60 seconds or so. The rest of the EE backend typically responds in a couple of seconds. >.<