Thanks to @goodekat for the reprex ```r library(plotly) library(tidyr) m <- matrix(rnorm(9), nrow = 3, ncol = 3) m_gathered <- data.frame(m) %>% gather(key = column) %>% mutate(row = factor(rep(c("X1", "X2", "X3"), 3))) %>% select(column, row, value) p <- ggplot(m_gathered, aes(x = column, y = row, fill = value)) + geom_tile() # Apply plotly to ggplot heatmap - deadspace in the middle of (X1, X1) ggplotly(p) ```  The fix seems easy -- change `hoverinfo="none"` to `hoverinfo="skip"` when creating the colorbar trace https://github.com/ropensci/plotly/blob/7031a25474f0dc275d20897810682c530cd1fbf3/R/ggplotly.R#L1303