(BUG) All devices ‘unavailable’ sometimes
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-  [x] That _OAuth_ is Enabled for the SmartApp under the IDE.
-  [x] The SmartApp and Device Handler are using the latest code available.
-  [x] That Both the SmartApps and Device Handlers have been _Published for You_ in the IDE.

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## About Your Setup
-  How many devices are detected?: All of then
-  Mobile App Version(Not required):
-  SmartApp Version: 2.3.8
-  Device Handler Version: 2.3.3
-  Homebridge Version: 1.2.3
-  NodeJS Version: 12.11.1

## Expected Behavior
All devices showing their status

## Current Behavior
Around 1 in 10 times opening Home app, all devices show ‘unavailable’

## Steps to Reproduce (for bugs)
**Provide a link to a live example, or an unambiguous set of steps to reproduce this bug. Include code to reproduce, if relevant**

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## Context
Running the 2.3.8 SmartThings homebridge app and since the major update from 2.3.6, I’m getting a weird issue. If I open the home app using an iPhone 11, the device screen will sometimes hang and then say all devices are unavailable. 
If I tap any device (shown in the first photo) it will change from ‘no response’, and it will operate or if I navigate off the the initial screen to a room and then back, all devices then show fine. Waiting for a while on the initial screen changes nothing and they all show unavailable until I do something.
This happens about 1 in 10 times I open the home app.

Homebridge running on a RPi3B+.
Homekit server is a Apple TV4 with iPad 8th Gen as backup.

This issue also creates a bigger problem that if I request an action via Siri on the iOS device to operate something, Siri reports that ‘it didn’t hear back from the device’. Takes a 2nd request to do it.

I have phone screenshots showing issues too.

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Please include a copy of any relevant log output to assist in tracking down the bug
