Having sent Tech Support details of the problem, I decided to go ahead and do a full re-install after deleting the BB folder and the Realband folder and doing an uninstall of BB Server.
This had a positive result by showing only 4 Realtracks missing:-
RT 229. RT 239, RT 247 and BonusPak.
I downloaded these again in case mine were corrupted and re-installed, but the results were the same.

However, on further investigation, it appears that only 2 RT's are missing, as follows:-
** N/A ** RT2552: Guitar, Acoustic, Fingerpicking Songwriter16ths Ev16 075 , Joe Robinson
** N/A ** RT2553: Guitar, Acoustic, Fingerpicking Songwriter16thsHigh Ev16 075 , Joe Robinson

Although RT 239 is showing in the N/A list, after loading it, all instruments were there. Confusing?

So, is there a way to get RT's 2552 and 2553 individually? as this would seem to complete the whole set.

Still waiting for response to this from Tech Support.

Any ideas guys?

BIAB 2017 Everything, RB 2017
Lenovo All-in-One. i5, 8gb Ram, 1 TB SHDD, Windows 10
Presonus AudioBox,Studio One 3, Behringer Xenyx302,
M-Audio Axiom 61, Samson Graphite 49.
Lenove Flex 15, i3,Windows 10