[R] Warning message: In length(barlist) == 1 && as.character(barlist[[1]][[2]]) == "1"

[Giozz Lau]

Hello,

I am writing to seek assistance regarding a warning message that I
encountered while running a CLMM with two main factors and one random
factor ("participants"). One of the main factors consists of six
levels that can be either categorical or numerical.

As this is my first time running this type of model, I would greatly
appreciate your expertise in understanding and resolving this issue.

Thank you in advance for your time and support.

Sincerely,

Gio.