I have two, and mine have never done that, but i am very careful to not overfeed, and i am also careful not to serve extremely large portions. I break it down to smaller bites. I also feed 2-3 times a week, with a week here and there being lighter with only 1-2 feedings a week. Every once in awhile I also give a 4-5 day break from feedings, maybe once every 6 weeks. I also dont feed until the eel refuses to eat. I feed regulated portions, and generally every feeding i leave the eels wanting, or at least willing, to eat more.
I changed to this routine after one of the eels went on a hunger strike.
I have no idea if my feeding method is a good one, but it has been working for me. Sometimes i still feel like my eels look obese, but they aren't lethargic like other eels i have seen.
I know another local who has one and he feeds daily. His never leaves his den. You dont ever even see it. It sticks its head out at feeding time for 3 minutes and that all you see of it for the day. It also goes on regular hunger strikes.
While mine dont actively hunt, they do leave their dens about every other day for an hour or so and openly swim. They also are always sticking their heads out of their dens etc. Not nearly a cryptic as the other local reefers snowflake.
I cant imagine its healthy long term for a snowflake eel to do little other movement besides death roles every day at feeding and then laying lethargic all other times.
Like i said, i have no idea if my success will work for others, but it has worked for me so far.