Maybe this will help you fix it.
In BC Online (v26.0), the test libraries (Test Runner, Library Assert, etc.) are available but not installed by default in your environment. That’s why you're unable to download symbols for them.
What to do:
1. Go to Extension Management in BC.
2. Click Manage > Extension Marketplace.
3. Search for and install the following:
Test Runner
Library Assert
Any other required test libraries (e.g., Library Variable Storage)
Once installed, you should be able to:
Add the dependencies in app.json
Download symbols
Use the AL Test Tool
Let me know if you want the exact app.json dependency format.
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