Description of bug / unexpected behavior
The following two part texts do not work properly:
{_0|w=34px|bgcol=red|txtcol=#FFF|left} {_u|w=40px|bgcol=#66F|txtcol=yellow|align=left}
{_0|w=34px|bgcol=red|txtcol=#FFF|left}{_u|w=40px|bgcol=#66F|txtcol=yellow|align=left}
In both cases, the placeholders are not replaced and not even the default input fields are shown.
Thanks to my colleague @dbauer-ets for spotting this.