Issue after save file (Edit Tool : Option font-size)

I noticed that the option to edit the font size in a blog or topic.
Something is happening irregularly. Sometimes you edit the text size and after saving the topic or blog that created the text, it simply remains at the default size.
As if the font size options were not working.
I have been wanting to report this for a few days, but I wanted to make sure that this is happening. After a moderator reported the incident, I was sure that this is really happening.

The process is simple

Create a blog or topic.
Set new text sizes. At some point during editing, it will stop working, so you will be unable to set sizes for your text.