[RTE]: On serialize deserialize numerable lists disappears

- [yes] I am running the latest version
- [yes] I checked the documentation and found no answer
- [yes] I checked to make sure that this issue has not already been filed

## Description

On serialize deserialize numerable lists disappears

## Steps to Reproduce

1. Open RTE
2. Add numerable list ( dont type anything else )
3. Serialize value to MD
4. Deserialize value

## Actual result

There isn't any numerable list

## Expected result

There is numerable list

## Environment

* UUI version: 6.3.0
* Browser name: Chrome
* Operating System: Windows