Hello there,
I am sorry for the delay in my response.
We have tried to replicate this issue at our end but we aren’t able to replicate the issue. We suspect that it may be due to a plugin or theme conflict.
Will it be possible for you to perform a conflict test on your site? You may need to temporarily disable all other plugins except the Email Subscribers plugin and switch to a default WordPress theme.
We recommend doing the troubleshooting using the Health Check plugin which disables all the plugins and switches the current theme to the default theme only for the current logged-in user when troubleshooting mode is enabled. It does not affect other users or site visitors. You can get the Health Check plugin from here. After enabling the troubleshooting mode in Health Check plugin, activate the Email Subscribers plugin, and check if the issue is resolved or not.
If it is resolved, then you can activate plugins one by one or switch to the current theme and check which is causing the issue.
If the issue persists with only Email Subscribers active, do let us know if this is the case. We may then need to debug it further.
Hope this helps you.
Let us know what comes out. Also, let us know if you have any further queries.
Thank you.