How to sum attributes from table cells?

Troubleshooting
1

I would like to track time in mostly every accessible datum in SB.

```template
**Time tracked**: {{
  sum('took', {page      where page = @page.name}) +
  sum('took', {task      where page = @page.name}) +
  sum('took', {paragraph where page = @page.name}) +
  sum('took', {table     where page = @page.name}) +
  sum('took', {header    where page = @page.name}) +
  sum('took', {item      where page = @page.name})
}} minutes.
```

It does not seem to sum table cells for some reason, e.g.,

Foo |
----|
Bar [took: 123] |
Baz [took: 321] |

Any ideas how to solve this? Thank you.