Compressor 4. What Does a Grey Down Arrow Mean?

I prefer to send projects from FCPX ver. 10.4.4 to Compressor 4.4.3 for rendering. I prefer to use adjustment layers created in Motion to contain any effects. Frequently, I get a large grey box that contains a down arrow (see attached) prior to selecting Start Batch. This grey box then shows up as a single frame at the beginning of each video. Things that will cause the grey box are the following:

• More than 3 effects in an adjustment layer.
• More than one adjustment layer.

Rendering projects directly from FCPX do not result in the grey box. Also, I if I use the same effects without an adjustment layer I do not the get the grey box. I suspect there is an issue with the adjustment layers created in Motion. I have confirmed that the adjustment layers have the same attributes as the base video, i.e. video type, frame rate, aspect ratio of the pixels.

I have been stumped with this for several weeks and have no idea what grey box means and what to try next.

Thank you in advance for your help.

Don Barar