`mcmc_pairs()` works differently on an HPC cluster?

[JasonPekos]

I can create pairs plots fine on my laptop.

mcmc_pairs(mcmc_out$draws(), np = nuts_params(mcmc_out))

When I run the identical code on the Sharcnet HPC system, if I include np = nuts_params(mcmc_out), the code will fail with the error:

Error in `geom_point()`:
! Problem while computing aesthetics.
ℹ Error occurred in the 2nd layer.
Caused by error in `check_aesthetics()`:
! Aesthetics must be either length 1 or the same as the data (15000)
✖ Fix the following mappings: `colour` and `size`
Run `rlang::last_error()` to see where the error occurred.

[ASKurz]

I'm running into this problem with brm() models (brms 2.18.0; bayesplot 1.10.0).