ggplot2 – How to plot several outcomes for several groups in R ggplot?

I want to build a single graph displaying several outcomes (with different point- and lineshapes for each, respectively) for several strata (displayed in different colours) over time. Using this for one group works:

data <- data.frame(
  time = rep(c("Baseline", "Follow-Up 1", "Follow-Up 2"), each = 8),
  stratum = rep(c("Intervention", "Control"), 12),
  outcome = rep(c("Sensitivity", "Specificity", "PPV", "NPV"), 3, each = 2),
  value = runif(24)
)

# working
data %>% 
  filter(stratum == "Intervention") %>% 
  ggplot(aes(x = time, y = value, group = outcome, colour = stratum)) +
  geom_point(aes(shape = outcome)) +
  geom_line(aes(linetype = outcome))

# not working
data %>% 
  ggplot(aes(x = time, y = value, group = outcome, colour = stratum)) +
  geom_point(aes(shape = outcome)) +
  geom_line(aes(linetype = outcome))

Graph displaying what I want for one stratum, the other should ideally just be added within the same graph with another colour under “stratum” in the legend

If I want the same for both strata it does not and produces following error:

Error in `f()`:
! geom_path: If you are using dotted or dashed lines, colour, size and linetype must be constant over the line
Run `rlang::last_error()` to see where the error occurred.

The info in last_error() does not help me. Has anyone a solution here?

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