Hello! I have a similar thing, I have found that my lo will have a brilliant morning nap (usually i have to wake her up from it) but just catnaps for the rest of the day.
What I worked out recently is that that nap doesn't have to be in the morning but can be any time of the day - if we're out and about she doesn't nap longer than 20 - 30 minutes, and I found that if we're out in the morning she'll nap better in the afternoon. And as long as she has that long nap at least once a day, the catnapping doesn't really affect her night time sleep (she sleeps really well - usually 12 hours a night), so I'm not obsessing about it.
Although, as I'm learning - as soon as I think she does things one way, she completely changes and does it a completely different way!!! xx