Up to version 7 font height was arbitrarily limited to 24 pixels. You can try version 8 uploaded now with this limit raised to 32 (the debug binaries I sent you, twobob, also had this limit at 32, which might explain why it worked once and then stopped. Version 8 is completely untested by me.
http://my.svgalib.org/kindle/myts-8.zip
http://my.svgalib.org/kindle/myts-8.tgz