Howdy quickrick,
Thanks for giving those a go! I would love to help you with this.
To be upfront we actually don’t support themes that call the_title() outside of the loop. Typically the problem you’re experiencing is caused by this. Doing that is a violation of WP standards, and the reason is because it causes problems such as yours with no real way for a plugin (ours included) to fix it.
That said we still do our utmost to help. It will require modifying your theme though. The last part of the guide you linked to (here it is again) tells your to modify where the_title() is output in your theme. Likely you will find itnside of header.php or archive.php. When you tried wrapping that in conditionals, what happened? Nothing? If so, what happens if you comment out/hide that piece of code. If the incorrect title doesn’t disappear, then you’re not looking at the right the_title(). Somewhere else in your theme it is calling the_title() again, or perhaps get_the_title().
Alternatively it is possible that your parent theme has corrected this in a more recent version, and that theme will be compatible with our latest version. You could try updating it. But it looks to me like this might be a more complex method as your theme seems to be heavily modified.
Does that all make sense? Please let me know.
Cheers!
– Brook