I hesitated to raise this issue because I've probably made a real rookie mistake somewhere. My Contribution Pages work fine in production mode but the transactions are not recorded in CiviCRM when I use Test Mode. All my Contribution Pages are affected. I posted an earlier question Contribution Pages are not working in Test-Drive Mode about this when I thought that all Tests were failing. Here's the screenshot iATS log in CiviCRM
It shows that $1.00 transactions in Test Mode are OK. Test transactions for other amounts are Rejected. What am I missing? Is this a CiviCRM problem or an iATS problem? (CiviCRM 5.48.0 on WordPress Version 5.9.3)