Official comment
We are sorry to hear you are having issues uploading your imagery. We throttle the number of files new users can upload to discourage running large amounts of data through the system before you have run smaller works through first. It is important to know what works and what doesn't before you spend a lot of points.
The maximum number of images that can be uploaded to the system goes up as you process more maps. To start, the maximum is the greater of 600 or 300 images per map you have run. For example, to run a 1000 image map you would need to have at least 4 maps processed first.
You can see this in Step 4 of the upload where is says the following:
"Maximum goes up 300 images for each map that gets processed up to the maximum of 4000."
We encourage you to run increasingly complex jobs to learn your way around the system but you would technically be able to continue with your intended dataset as long as you have the required number of maps in the system. They can be free/small if needed.
The part about 2,148 images is just telling you how many images you can run in total.
