Unstable test result

Good day!
We need at least some ideas why this is happening :'(

**Environment**
backstopjs 5.0.1
Docker version 19.03.12, build 48a66213fe
Properties in backstop.json
```
"engine": "puppeteer",
"engineOptions": {
"args": [
"--no-sandbox"
]
},
"dockerOptions": {"args": ["-it"]},
"asyncCaptureLimit": 8,
"asyncCompareLimit": 500,
"debug": false,
"debugWindow": false,
"dockerCommandTemplate": "docker run --rm --mount type = bind, source = \" {cwd} \ ", target = / src backstopjs / backstopjs: latest {backstopCommand} {args}"
```
}

**Сase**
1. I run 1 test in a circle
2. The test result changes
50% test successful
25% test crashes with "Reference image not found" error
25% the test crashes with the error "Test image not found"

locally, under windows, works perfectly

on a remote server under debian it works as described above, tried several servers with similar settings - the same

@ghiden maybe there is at least 1 idea in which direction to think?