As per recent developments, tracked URLs can fail when URL signature is active in Campaign. Some mailboxes can be more impacted than others, as some companies have specific security tools which can impact links and alter the URL signature mechanism.
If you are impacted by this, then refer to the guideline documentation for best practices and recommendations along with the steps to do it.
In case you have any questions, please feel free to post them below or reach out through the community Q and A section. In case you have any ideas and/or suggestions regarding the Campaign Classic product, then kindly submit them here.