I should think that in 1917 the interrupter was a fairly complex mechanism, prone to jams, Actually the unit for the rotory's was a straight forward design, while the inline was a mechanical nightmare.
The Machine Gun itself while complex is rather smooth in operation, if you don't feed it bent bullets.
Ammo of the day arrived in bulk, say 1000 rounds of .303. The base armorer had the task of putting them in belts, he physically spotted the badly bent ones, and rejected their use. But human hands, make human errors. Actually they needed a go-no go chamber to test the feedability of the round, but few had the time, or the ambition. There's the WAR you know . . So do Carry On, and take this wooden hammer to beat on your guns
To that end, I should think there'd be less jams with a Lewis Gun, simply because you need to watch what you're doing when loading the magazine. Plus in the majority of cases, no interrupter mechanizm was used