I am aware that as of https://www.swtor.com/patchnotes/08192025/game-update-7.7.1-flashpoint-resurgence
Players who have a Security Key tied to their account will only receive their Cartel Coin grants if they were active in the last 29 days. We will not be removing coins that have already been granted. To add a Security Key to your SWTOR account, go to your account page on our website. All commonly used authenticators are accepted.
Unsure if this has any relation to the coins you have received
you can email mailto:support@swtor.com and they should be able to advise