Quick answer: Unity Test Runner can't find tests in asmdef tagged 'editor-only'? Test Runner runs editor scope; asmdef must include Editor platform.
Move tests to a 'mobile-tests' asmdef; tests disappear from Test Runner.
Add Editor to test asmdef
asmdef Platforms includes Editor explicitly. Test Runner sees tests.
Or use Test Framework's Tests Includes Reference
Separate test asmdef references the production asmdef. Tests editor-only; production multi-platform.
Audit each test asmdef
Platforms list. Editor present = visible.
“Test discovery is platform-scoped. Editor must be in the scope.”
Standardize on 'all test asmdefs include Editor + target platform'. Tests discoverable; production targeted.