Pause action not working

I need to wait for some elements to load on the page for my test, but whenever I try and use the pause action, it returns undefined?
Even when I've recorded the action via hux --record, it doesn't seem to like it... Here's my json:

```
[
{
"action": "screenshot"
},
{
"action": "pause",
"ms": 5896
},
{
"action": "screenshot"
},
{
"action": "pause",
"ms": 3218
},
{
"action": "click",
"y": 318,
"x": 702
},
{
"action": "pause",
"ms": 1608
},
{
"action": "click",
"y": 318,
"x": 554
},
{
"action": "pause",
"ms": 1758
},
{
"action": "screenshot"
}
]
```

and my terminal Output:

```

---
Replaying and writing screenshots for "toggle button"

---
Taking screenshot 1
Pause for undefined ms
Clicking (570, 316)
Taking screenshot 2
Clicking (135, 164)
Clicking (43, 382)
Taking screenshot 3
```

Any help appreciated!

Start by reproducing the issue with the supplied action JSON and compare the pause action's replay handling with the terminal output. Trace the pause action entry point to determine why the recorded ms value becomes undefined; done when pause waits for the requested duration and the output reports that duration.

Written by the indexing model from the issue text.