I've found another bug in the detachable panel feature.
When the panel is attached as normal in the workspace, entering a value in the Key field (eg. title) in the ATTRIBUTES section and then hitting the Tab key advances the cursor to the Value field, as expected.
When the panel is detached, entering a value in the Key field and hitting the Tab key causes a new set of attribute fields to be created below, and automatically moves the cursor into the Value field of the new set.
Here is a video demonstrating the behavior. Bootstrap Studio 5.4.1 on Windows 7 Machine.