In my experience, pony tail palms are really sensitive to too much water and/or having too much mulch near their trunks. Have you mulched them recently? Have they gotten more rain than they need? That might leave them vulnerable to bugs/slugs.
I had one in a pot for several years and put it out into the yard about a year ago. One of the three stems went great guns. It's four-feet high now, from six inches. The other two did not like their conditions and I think both have died.
I do think they're really sensitive to getting too wet or having mulch too close to their trunks/being planted too deep.

Something chewed on the new growth. Probably snails. As far as the overall condition of the plants, make sure the pots are well-drained and the soil is mostly sand. Ponytail Palms suffer quickly from too much water.

Thanks for responses. Didn't mean to disappear; I went away for 2 weeks.

No, they have no mulch; but we used potting soil and the original dirt they came in. Have had a lot of heavy rains, but no puddling, so seem to be draining ok.

I will just watch them and see what happens, and will decide what to do next spring.

Thank you!

Wondering if lubber grasshoppers like that tender new growth?

Alternately, some caterpillars or other insects can get into the center of plants & a small nibble becomes very dramatic-looking as the leaves enlarge & emergeâ¦.

I bought my ponytail palm at 40cm over 15yrs ago and is now around 6ft n noticed it lacking new. Growth and discoloured leaves upon closer inspection it's bulb underneath from the centre outwards approximately 25cm all round very dry the last 10-15 CMS very wet and large pockets of slugs in groups of 7 or 8 eating into my ponytail??????

Please help my beloved ponytail