Not me. Can you still use your 240 after getting this message? Supposedly, there is a 10,000 song limit, or at least that was the case on the AK120. You could try a reboot (hold down the power button for 12 seconds) and see if that resolves the issue. I hope everything turns out fine ...
One problem I'm noticing on mine is that my battery will not fully charge using my USB3 connector on my MacBook Air. The manual says something about this, but I assumed that would be the case if you used a hub or a USB output on a keyboard. I've been burning my unit in for the past few days, so I thought the problem was that I was playing files while charging the battery. This morning, I stopped playing files and just let it charge. Back from school 5 hours later and the 240 is only half way charged. I did set my energy preferences on my MacBook to not go to sleep.
I'm going to use the wall charger that came with my iPhone to see if this rectifies the problem.
Here's what happened. After trying many different ways, plugging and unplugging I was finally able to transfer again and I do not know why. I was NOT transferring into the music folder. Which did not seem to matter anyway. I reset, erased all and am now copying again this time into sub folders in the Music folder. You should see two folder under Music, downloads and another containing pre-loaded music. I lost the pre-loaded 10 songs when I reset. No biggie, A&K will send me the link to get those back. So, your music folder should be inside the music folder. I knew that on the AK120 but did not think it mattered here and apparently it does.
The problem with the Android App for MAC is once folders fill up the window showing the AK's drive, there is no place to 'put' a new folder. So, folders copy into folders. Make sure you leave room with a few single songs so you can drag a folder on top of the single file and then it will copy as a folder on its own.