facet_wrap causing NA values

The upper tile in the following example is changed by ggplotly. I assume it is grey because it is somehow NA. Only occurs when faceting is used.

test <- structure(list(week = c(7L, 7L, 32L), day = structure(c(5L, 6L, 
1L), .Label = c("Mon", "Tues", "Wed", "Thurs", "Fri", "Sat", 
"Sun"), class = c("ordered", "factor")), year = c(2017, 2017, 
2015), `Samples #` = c(31L, 49L, 20L)), class = c("tbl_df", "tbl", 
"data.frame"), row.names = c(NA, -3L), .Names = c("week", "day", 
"year", "Samples #"))

p <- ggplot(data = test, aes(x = day, y = week, fill = `Samples #`, height = 1)) +
geom_tile() +
facet_wrap(~year, ncol = 1) 

p

ggplotly(p)

首先运行提供的 R 复现代码，使用 ggplot、geom_tile、facet_wrap 和 ggplotly(p)，然后将分面输出与原始图进行比较。使用分面时，如果上方的 tile 保持正确的值和外观，而不是变成灰色或 NA，则表示完成。