Hello. Thank you for contacting the Toolset support.
Well - I checked on my local test install with minimum setup (Only Toolset plugins active with default theme active) but I do not able to reproduce this issue.
To debug this issue further and rule out any side effect of any third party plugin or theme you are using:
Could you please try to resolve your issue by deactivating all third-party plugins as well as the default theme to check for any possible conflicts with any of the plugins or themes?
If the above step does not help: I need access to details of your install.
*** Please make a FULL BACKUP of your database and website.***
I would also eventually need to request temporary access (WP-Admin and FTP) to your site. Preferably to a test site where the problem has been replicated if possible in order to be of better help and check if some configurations might need to be changed.
I would additionally need your permission to de- and re-activate Plugins and the Theme, and to change configurations on the site. This is also a reason the backup is really important. If you agree to this, please use the form fields I have enabled below to provide temporary access details (wp-admin and FTP).
I have set the next reply to private which means only you and I have access to it.
The code in the content template that I am using is the following. This code works perfectly well with PHP 5.6 but not with PHP 7.2. However,I noticed that if I remove the <span> from the {su_tab] title shortcode, it works.
Why would that matter especially if this was not an issue with PHP 5.6?
Well - [su_tab] is not the shorcode that belongs to Toolset.
If you remove the [su_tab] shortcode and the Toolset shortcodes you added to content template works fine - that means this issue do not belong to Toolset but the [su_tab].
Can you confirm - what you see when you remove [su_tab] shortcode. If this issue confirms, you should contact [su_tab] plugin/theme support.
If the issue is from Toolset, we are happy to help you further. Could you please try the above steps and let share your feedback.