I have tried to reproduce this issue but failed. Make sure you properly settings the WP User Frontend. If the issue still persists then check for your theme or plugin conflicts. You can disable all your plugins except User Frontend and switch to a default theme of WordPress like- Twenty Twelve, Twenty Thirteen, Twenty Fourteen. Also do you have latest version of WP User Frontend Pro ? If not please update the latest version WP User Frontend Pro and let me know the result.
Yes, you are right there are not place holder in “Rich Text-area” and “Teeny Rich Text-area”. We do not have this feature right now. Place holder uses for pointing user to identify “it is a place for writing something”. Which basically uses in normal text-area.