Sounds like you have identified the most likely cause. I tell students
to watch the spot on approach, then when it is in "point blank range"
there is no need to look at it any more, and it's time to look at the
other end of the runway.

Tom Knauff has students stand near the runway and bend at the knees to
simulate the last part of the landing hold-off. You look down the
runway and note the perspective changes that are the cues you need to
maintain a slow descent. For a comparison you can also look at the
ground near your feet to see how ineffective this is.

Cats wrote:
I am one of those people with ongoing intermittent landing problems. I
have good patches - managed to get solo recently - and then bad
patches. The bad patches probably co-incide with forgetting to look up
as I start the round-out, so there is no hold-off and a rather heavy
landing, sometimes with a bounce.

I've got my own ideas on how to address this, was curious if anyone
else here has had the same problem and if so, how did you deal with it?
Unfortunately I reckon I developed the bad habit fairly early in my
flying, as it was well-established by the time someone pointed out what
was going on. Since I seem to be reasonably good at doing what I'm
told to do, via a route from ears to hands & feet that misses my brain,
I suspect I've flattered to deceive in the front seat.