Applied these three changes; afterwards writing `{F1234}` in the Task Comment text field finally rendered the image preview in the preview area, plus I could successfully add the Comment.
Additional cute tests:
```
Test alt:
{F1234,alt=0}
{F1234,alt=null}
{F1234,alt=123}
{F1234,alt=0.1}
{F1234,alt=[]}
Test width:
{F1234,width=0}
{F1234,width=10}
{F1234,width=10.1}
{F1234,width=10%}
{F1234,width=49.99%}
{F1234,width=100%}
Test height:
{F1234,height=0}
{F1234,height=10}
{F1234,height=10.1}
{F1234,height=10%}
{F1234,height=49.99%}
{F1234,height=100%}
Test mix width/height:
{F1234,height=0,width=0}
{F1234,height=10,width=15}
{F1234,height=10.1,width=15}
{F1234,height=10%,width=15%}
{F1234,height=49.99%,width=15%}
{F1234,height=100%,width=15%}
```
If you have no nuclear implosion and if dimensions are somehow respected and the alt text works, well done! Test passed.