Can't use '.' period as code completion trigger character when next to a word

Describe the bug

Code completions defined within a custom VS Code extension don't appear when the trigger character is a period next to a word with the RedHat YAML extension enabled. They appear as expected when the RedHat YAML extension is turned off or when the period is typed next to a space.

Expected Behavior

Code completions should appear, displaying "error", "log" and "warn"

Current Behavior

Code completions don't appear.

Steps to Reproduce

1. Clone https://github.com/microsoft/vscode-extension-samples and open completions-sample folder VS Code
2. In completions-sample/src/extension.ts, remove definition and usages of provider1.
3. In completions-sample/src/extension.ts, change 'plaintext' to { scheme: 'file', language: 'yaml' }.
4. Run npm install in completions-sample folder (see root README for NPM and NodeJS version requirements).
5. Hit F5
6. In the Extension Development Host that opens up, make sure RedHat YAML extension is installed and enabled
7. Create a YAML file with the following contents:
   name: test
8. Type '.' next to test without spaces

Environment

• Windows
• Mac
• Linux
• other (please specify)

Reproduce the issue using completions-sample/src/extension.ts after following the listed setup and running npm install, then test the Extension Development Host with the RedHat YAML extension enabled. Trace why a period adjacent to a word suppresses the expected "error", "log" and "warn" completions; done means those completions appear in the YAML file without spaces.