I conducted a Negative Binomial GLMM analysis on the dataset, and the results showed a significant difference with a P-value below 0.05 when I performed post hoc analyses, specifically pairwise comparisons. However, when I applied lettering to the dataset to further explore differences between groups, I found no significant distinctions. I'm unsure how to interpret these conflicting results.

I would appreciate your insights and advice on how to best address and interpret these findings.