Isochrone generation hangs for specific lat lon

I am trying to generate isochrones for a set of points and I encounter some cases where the valhalla stops responding.

Examples of payload used for the `/isochrone` endpoint (http call):

```json
{
"locations": [
{
"lat": 40.868612720356,
"lon": -84.066352844238
}
],
"costing": "pedestrian",
"polygons": true,
"contours": [
{
"time": 10.0,
"color": "ff0000"
}
]
}
```
```json
{
"locations": [
{
"lat": 36.693474497941,
"lon": -119.139518737793
}
],
"costing": "pedestrian",
"polygons": true,
"contours": [
{
"time": 10.0,
"color": "ff0000"
}
]
}
```

```json
{
"locations": [
{
"lat": 40.219519220276,
"lon": -82.91072845459
}
],
"costing": "pedestrian",
"polygons": true,
"contours": [
{
"time": 10.0,
"color": "ff0000"
}
]
}
```

_Expectation_: A polygon of the isochrone is returned.
_Actual_: No response from the server.

Other information:
- when running the server with 1 active request only. the cpu usage of the server remains around `1000m` (1vCPU is used to process 1 request, and stays at 1 vCPU)
- cancelling the request, doesn't result in the computation stoping / the cpu usage going back down.
- the problem remains when using [pyvalhalla](https://github.com/gis-ops/pyvalhalla) as well. its unlikely an issue with the server or an issue with the python bindings, since these points cause problem for both.
- the systems works fine (as intended) for a huge majority of points that I was calculating.

I have also tried calling https://valhalla1.openstreetmap.de/isochrone twice for the point `40.219519220276 -82.91072845459` to check if my valhalla setup is working as intended, and it resulted in a timeout: `The server didn't respond in time`