ox-ascii is putting a blank line between a table and a following
caption.
It is not doing this for listing captions so, IMHO, it is a bug.
Here is a (very small) patch which fixes the problem.
diff --git a/lisp/ox-ascii.el b/lisp/ox-ascii.el
index 59d0152..3baf4bd 100644
--- a/lisp/ox-ascii.el
+++ b/lisp/ox-ascii.el
@@ -1658,7 +1658,7 @@ contextual information."
(t (org-remove-indentation (org-element-property :value table))))
;; Possible add a caption string below.
(when (and caption (not org-ascii-caption-above))
- (concat "\n" caption)))))
+ caption))))
rick