Which browser are you using?
Do you have the same with a different browser?

Only ever use Ubuntu Firefox currently 40.0.3

Will try opera: . . . Ok have tried Opera and is exactly the same :)

Thanks

OK with the code on the posts page. It's not the fourth post that's significant, which I thought couldn't really make sense but something below Filters (Reset Filters).

Oh! I've just noticed another one on the Posts List page, at the bottom above the (Reset all Filters)

If I click on [Reset Filters] both that option and the one at the bottom (Reset All Filters) disappear, which makes sense. But if I click on the code they reappear as the code is in a link.

<a class="action_icon btn btn-warning btn-sm hoverlink" href="?ctrl=items&amp;blog=5&amp;filter=reset" title="Reset all filters!">
<span title="Reset all filters!" class="fa fa-filter"></span>Reset filters

Looking at the source code there are five uses of [fa fa-filter] and only the first one is an issue and in that case the quotes are not escaped <span title="Reset all filters!" class="fa fa-filter"></span>plus it's an empty span.

Forget all the above

I've found it.

I had a validation error and my solution caused this problem, I think:
See http://forums.b2evolution.net/html5-validations-in-6-6-3

By changing tag to data-tag the code is the value of the button??

<input data-tag="input" type="submit" class="search btn-info pull-right btn" tag="button" value="&lt;span class=&quot;fa fa-filter&quot; title=&quot;Filter&quot;&gt;&lt;/span&gt; Filter" />

As tag is not an acceptable attribute in HTML5 according to https://validator.w3.org/nu/ I hacked the code as explained in my post mentioned above.

Off to sleep now, will pick up on this later, thanks

Just realised why I found it hard to find this post, I put it in the wrong forum. Would someone please move it to (b2evolution Support) please?

Thanks