Code Block Bug – HTML tags stripped out when in Draft

So this is a weird bug. It took me a while to work out why it was happening. Turns out it happens on draft pages but working fine on published pages.

I’m using the Code Block element and had a line: <div class="service-toggle"><i class="fal fa-chevron-down"></i></div>. On the published page, this was outputting fine. On a duplicate version of the same page, which was still in Draft, it was only outputting: <div class="service-toggle"></div>.
If I added another tag inside “service-toggle” e.g. <div class="service-toggle"><i class="fal fa-chevron-down"></i><span>test</span></div>, it would display the icon and the word ‘test’, however, the <span> and </span> had been stripped out: <div class="service-toggle"><i class="fal fa-chevron-down"></i>test</div>.

Only when I publish the page, all the tags are outputted as they should.