To reproduce this issue
1. Set up full stack. Set AM token lifetime to 1 hour. Set AM session max idle time to 1 hour.
2. Start OIDC flow, https://backstage.forgerock.com/knowledge/kb/article/a45321184.
3. Randomly execute REST call to IDM (such as step 5 in the KB) in the first 30 minutes. For each REST call to IDM, there is a corresponding "_action=validate" from IDM to AM.
4. After 30 minutes, execute the same REST call to IDM, and the result is.
This time, there is no "_action=validate" from IDM to AM.