The other question I was going to ask was where the lyric sheets were first 'built' before they ended up in ST.
I have found that if they start in Word (or other word processor), even if started by someone copy & pasting from a webpage into Word, and then edited in Word before being copy & pasted into a text file for importing into ST, that stray special characters and tabs can sneak in and throw out text spacing.
I use Word documents as the 'master' for our lyric sheets (before copying into a text file to import into ST) and I now make sure I turn on the Show special characters feature at some point to pick up stray Tab characters.
If you want to share 1-2 of your lyric sheets that are displaying this issue, I'd ben happy to take a look, and then see if I see same issue with switching between Left and Centre alignment.
