Alright Hapax, thanks for the support!
I've got a pattern identified! thanks to the link you provided, I was able to cross test many of the code provided there (the ones without quick sprite).
It would seem that the behavior only occurs with renderTextures of sizes below 256*256; my 100*100200*200 illustration above created this phenomenon. SO as long as the renderTextures are above size 256*256, it works (Not sure why).
As to the version of SFML I am using and how I downloaded it: it was installed using the linux command line interface (cli) with the linux command line provided by SFML's website:
sudo apt-get install libsfml-dev
So, I think it should be up to date.
Now for the more interesting aspect, why does it not allow renderTextures of size smaller than 256 by 256(Update: one side can be smaller than 256, not both)?
I will be testing more..
Edit 1:
It would seem that atleast one dimension of the two, for renderTexture, must be atleast 256.
Have a renderTexture of 10*256 causes me no strange behavior, however if any of the sides were less than 256, say 255, then unknown behavior occurs.
Edit 2:
The size of the shape is irrelevant, if the shape is larger than the renderTexture, it just gets drawn out of the renderTexture like normal.
Edit 3:
The clear method of renderTexture still works at lower sizes, clearing with a color of red will produce a red clearance like normal, but the shape will be missing or distorted; I've only seen missing and single vertical line so far.
Edit 4:
Sprites on renderTextures smaller than 256 also do not behave like normal.
Does this apply to you as well? if not, is there any difference between sfml's implementation of renderTextures dependent on size and OpenGL version? If not then, worst case, it's probably just an OpenGL 1.3 issue.
Maybe I can use larger renderTextures (not saying I can't) and simply use sprites to subRect smaller images from the renderTextures, haha.
My reason for using small renderTextures:
I was using smaller renderWindows originally so I complemented it with smaller renderTextures; but I can work around it with sprites and subRects of the larger renderTexture to fit my needs.
It is interesting though, that small renderTextures behave differently on OpenGL 1.3 or is it for all OpenGL? And that larger renderTextures are no effected at all.