There were no ‘issues’ with baggage loading. ALG is right on the limit of performance of the LGW airbuses, so it just couldn’t make it there with a full load of pax and bags - they took the decision to fly the pax and leave the bags. It’s not the first time this has happened. Typically if loads were light the rest of the week they’d reflight the bags as and when, but subsequent flights were also busy so they sent the bags on a separate flight.

Note that there was no chartering in a new aircraft, they just sent one of their own down with no pax. The alternative would have been to run a 777 on the regular flight the next day, so presumably none was available.