The work around I have used in the past when I had Gold - create 3 identical slides with a 0 transition between them. Put the caption on the center slide. Now the "slide" will be without the caption for the duration of the first one, have a caption for the duration of the second, and then no caption for the third one. Note - you can use the same sort of trick to have a slide where it starts at one zoom level, zooms to a second level and then holds there for the duration.
You can't have too many gadgets or too much disk space !!
mikey (PSP6, Photoshop CS6, Vegas Pro 14, Acid 7, BluffTitler, Nikon D300s, D810)
Lots of PIC and Arduino microprocessor stuff too !!