so your board is using the Ambiq uploader … not the SVL… the only disadvantage is the time it takes to load… if you want you COULD add the SVL uploader GitHub - sparkfun/Apollo3_Uploader_SVL: The SparkFun Variable Loader (SVL) serial uploader used on SparkFun Apollo3 and Artemis boards. It does NOT replace the Ambiq uploader, which is part of the ROM, but it makes uploading faster… up to you!
Whenever you upload make sure the IDE monitor is CLOSED. It might display / pick-up feedback from the board that is mend for the uploader and as such uploading is failing.