Ovid's Metamorphoses 7.66, here I marked my attempt:
nempĕ tĕ/nens, quŏd ă/mo, grĕmĭ/oqu(e) in/ Iasŏnĭ/s haerens
That makes the 3 first feet dactyls and the fourth one a spondee, but the answer from hexameter.io says the fourth is yet another dactyl (and also mentions there is an elision, so I probably got the elision right; unfortunately I can't see the correct scan itself). The i in qu-in is parsed long, because the I of Iasonis is a consonant. I can't figure out what I missed.