Manuscript projects do not support panel tabset

Manuscript projects do not seem to support the panel tabset chunk option. Only writing the div elements directly will generate the tabset in the HTML document. See below for a reproducible example. Additionally, I get this warning with both approaches: "Warning: couldn't recognize format, using default tabset rendering"

---
title: "Tabset"
format: html
---

## Working

::: {.panel-tabset .column-page}

### Scatterplot

```{r}
#| echo: false
#| output: asis
plot(cars)
```

### Histogram

```{r}
#| echo: false
#| output: asis
hist(rnorm(40), nclass = 5)
```

:::

## Not working

```{r}
#| panel: tabset
#| output: asis
 
x <- list("Scatterplot" = plot(cars), "Histogram" = hist(rnorm(40), nclass = 5))

for (n in names(x)) {

    cat("###", n, "\n")

    print(x[[n]])

    cat("\n\n")

}
```

Start with the reproducible manuscript example in the issue and compare the direct panel-tabset markup with the chunk using the panel option. Trace the path that emits the “couldn't recognize format” warning and verify that the chunk form produces the same tabset in the HTML output without the warning.