Bencherished

@Splungeworthy Yes, but it's not late, as long as you still have your old phone with the play list. 
On the old phone, Poweramp- Settings- Export Settings/Data.
Select what you want, (in your case, play list only).
Choose a location you can access, then Export, after that, send the  file to the new phone, then Import Settings/Data. Browse to the folder you sent back up, click, and you're done.
Bencherished 

I am guessing, this only happens in a particular few songs?
If the answer to the above question is yes, then I will guess again, you edited some tags on the affected files? 
If the second answer is also yes, then the problem is with the files. 
It has been corrupted, just delete them and re-download and avoid editing a file when it is in use. 
But if all I wrote is not the case, please feel free to give more clarification. 
Bencherished 

Colours makes things look beautiful, I have above eight thousand MP3 songs, occupying 67GB on my SD CARD, they have mixed kbps, I do notice the difference if any is below 225kbps, so I delete and download a higher kbps. 
Having the colors will make it easier to sort out the low quality kbps. 

Go to settings, and enable > Automatically download missing album art. 
But know that some of the album art may not be correct ones and they are not embedded in the music files. 
I prefer having it embedded so they move along wherever they go. 
Use auto tagger.