In NH game I sold a 4yo for about £55000 2 days before season ended with no race entries. At end of season it appears as dead, poor thing

.
Do some AI trainers kill horses to get better replacements?
Also at end of season I noticed a couple of geldings retired with E behind Retired, not sure what that means.
Next weird thing, I had a horse that sulks if not in front, it had won 3 times CDG so in its next race I told jockey to make the pace but he held it up last in a slow run race. He no longer rides my horses.
Bill