As you say the Select 1.1 is very old firmware. There have been many previous reports similar to yours where locos configured on version 1.0 / 1.1 Selects are not recognised by RailMaster / eLink running the latest eLink firmware [version 1.07].
The solution is to use RailMaster / eLink to RESET the decoders in the locos [write a value of 8 to CV8], then readdress them with NEW addresses using RailMaster. Performing an 8 to CV8 factory reset will also revert the loco with the 4468 DCC address back to 03, where it can then be readdressed again to something more manageable.
I find it odd that you say that many of the locos are still address 03, this seems to infer that you do not seem to appreciate how DCC works and that all the locos should be given separate and unique DCC addresses [anything but 03].
You really need to devise a proper DCC addressing scheme. DCC Address 03 should be avoided on your layout so that you can always use DCC Address 03 to test a new loco / decoder purchase. It is prudent and good practice to test all new decoders on the factory address first for correct functionality, before you try to change any settings. That way, if something doesn't work afterwards, you know it is something you have done.
If you start at DCC Address 10 and then go 11, 12, 13 etc then 03 is left clear.
It seems to me, based upon what you have written in your post that you might be struggling with RailMaster in terms of how to 'Address a loco' and operate it using the software.
These tutorial posts of mine might assist in simplifying these basic tasks.
Using RM to change the address of an existing Loco
Using RM to read and write CVs
Manually adding a Loco to the RM Database.
Full description of the ‘Locomotive Settings’ screen in detail.
Setting up Flying Scotsman TTS Sound Functions.
If none of your locos have sound, then just ignore the 'sound' related steps in the tutorials. Look to MY posts in the threads linked above.
TIP: As a relatively new poster on the forum, just be aware that the 'Blue Button with the White Arrow' is not a 'Reply to this post' button. If you want to reply to any of the posts, scroll down and write your reply in the reply text box at the bottom of the page and click the Green 'Reply' button.
See also – further TIPs on how to get the best user experience from this forum.