Snapshots not updating or are blank.
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**Describe The Problem:**
As of the last day or so, none of my cameras return snapshots. They're just blank, and all Home apps (macOS, iOS, iPadOS) just show "now" perpetually in the snapshot timestamp field. All cameras still stream perfectly. Potentially related to UNVR Pro 2.3.10 firmware update? I believe it happened around the same time, but can't be sure.

**To Reproduce:**
- Open Home app
- Observe cameras

**Logs:**
<!-- In order to be helpful, include the relevant logs from Homebridge, if applicable. -->

```
[12/29/2021, 4:14:45 PM] [homebridge-unifi-protect] <REDACTED> NVR [UNVR-PRO]: Connected to the Protect controller API (REDACTED).
[12/29/2021, 4:14:45 PM] [homebridge-unifi-protect] <REDACTED> NVR [UNVR-PRO]: Connected to the UniFi realtime update events API.
[12/29/2021, 4:14:45 PM] [homebridge-unifi-protect] <REDACTED> NVR [UNVR-PRO]: Discovered camera: Office [UVC G3 Flex] (REDACTED).
[12/29/2021, 4:14:45 PM] [homebridge-unifi-protect] <REDACTED> NVR [UNVR-PRO]: Discovered camera: Family Room [UVC G4 Instant] (REDACTED).
[12/29/2021, 4:14:45 PM] [homebridge-unifi-protect] <REDACTED> NVR [UNVR-PRO]: Discovered camera: Garage [UVC G4 Pro] (REDACTED).
...
[12/29/2021, 4:14:45 PM] [homebridge-unifi-protect] <REDACTED> NVR [UNVR-PRO]: Controller refresh interval set to 15 seconds.
[12/29/2021, 4:14:45 PM] [homebridge-unifi-protect] <REDACTED> NVR [UNVR-PRO] Office [UVC G3 Flex]: Disabling motion sensor.
[12/29/2021, 4:14:45 PM] [homebridge-unifi-protect] <REDACTED> NVR [UNVR-PRO] Family Room [UVC G4 Instant]: Disabling motion sensor.
[12/29/2021, 4:14:45 PM] [homebridge-unifi-protect] <REDACTED> NVR [UNVR-PRO] Garage [UVC G4 Pro]: Disabling motion sensor.
...
```

**Homebridge Configuration:**

```json
{
    "controllers": [
        {
            "address": "...",
            "name": "UNVR Pro",
            "password": "...",
            "refreshInterval": 15,
            "username": "homebridge"
        }
    ],
    "options": [
        "Disable.Motion.Sensor",
        "Enable.Video.Stream.Only.High.10.1.1.3",
        "Enable.Video.Stream.Only.High.10.1.1.4",
        "Enable.Video.Stream.Only.High.10.1.1.5",
        "Enable.Video.Stream.Only.High.10.1.1.6",
        "Enable.Video.Stream.Only.High.10.1.1.7"
    ],
    "verboseFfmpeg": false,
    "_bridge": {
        "username": "...",
        "port": 36809
    },
    "platform": "UniFi Protect"
},
```

**Screenshots:**

![IMG_0946](https://user-images.githubusercontent.com/3916693/147712189-a65e82bd-726a-4e5d-8ba4-e09b718d31d5.PNG)

**Environment:**

* **Homebridge Version:** 1.3.9
* **Node Version:** 14.18.0
* **Homebridge-UniFi-Protect Plugin Version:** 4.4.3
* **UniFi Protect Version:** 1.20.3
* **UniFi Protect Controller Type:** UNVR-Pro
* **UniFi Protect Controller Firmware Version:** UNVR Pro 2.3.10
* **Apple Device and iOS / macOS / iPadOS / tvOS Version:** 15.2
* **Operating System and OS Version:** Ubuntu Server 20.04.3 LTS
