Something I noticed tonight.... existing clay ovens placed before the recent game update (1.15.9) would not allow fuel to be added nor could I light one with fuel in it already UNTIL I broke it down and replaced it.
Tested it in a new world; results were
vanilla = works as normal
Added EF 1.4.4 as the only mod = could not interact with existing oven.
Just something I thought worth mentioning in case others had the same issue. No crashes or anything, just unusable ovens until being replaced.