There have been intermittent reports in another thread of problems transferring to BAEC for the last year. Start at post
156 in April 2018 and skim forward. There is another cluster of reports in October.
Offer terms for reference:
Promotion Terms & Conditions
Bonus Avios offer is valid for point transfers to British Airways Executive Club completed between 12:00 AM ET on April 22, 2019 and 11:59 PM ET on June 16, 2019. Minimum transfer is 1,000 Ultimate Rewards points. Bonus Avios will be awarded by British Airways in your British Airways Executive Club account when your transfer is complete.
For the Bonus Avios offer, you will receive 30% Bonus Avios for each Ultimate Rewards point transferred during the promotional period listed above. For example, if you transfer 1,000 Ultimate Rewards points, you will receive a total of 1,300 Avios. You must be enrolled in British Airways Executive Club with both your membership in good standing and your Ultimate Rewards credit card account open and not in default in order to participate in this offer. Visit ba.com/executiveclub to enroll. Once you have transferred Ultimate Rewards points, they become Avios subject to the Terms and Conditions of the British Airways Executive Club and cannot be transferred back to your Chase Ultimate Rewards Program account. Taxes, government imposed fees, and all applicable carrier charges apply on British Airways redemption flights and upgrades. Individual airline carrier restrictions may apply. See British Airways Executive Club Terms and Conditions for details, including Avios redemption requirements, which can be found at ba.com/theclubterms. Reward flights and cabin upgrades are subject to availability. Chase is not responsible for availability of flights, accommodations, Avios or any other rewards in the British Airways Executive Club.