Text line switches uncontrollably in AlterEgo voice syntheziser

### Bug Summary
Text line switches uncontrollably in AlterEgo voice syntheziser

#### Steps to reproduce
Play AlterEgo Voice syntheziser with Nata or Bones voice banks plus singing notes and text. Singing hops between lines and within lines of text without clear reason. AlterEgo lines can be controlled via midi signals - probably LMMS1.3.0 is sending midi signals?

#### Expected behavior
Each syllable should follow the previous syllable.

#### Actual behavior
Singing hops between lines and within lines of text without clear reason.

#### Screenshot

#### Affected LMMS versions
lmms-1.3.0-alpha.1.102+g89fc6c960-mingw-win64

Finally, if possible, please test if the bug occurs on both stable and master.
Does not occur in LMMs 1.2.2.

Reproduce the issue by playing the AlterEgo voice synthesizer with the Nata or Bones voice bank, singing notes, and text; compare behavior with LMMS 1.2.2 and the affected 1.3.0 build. Trace the MIDI signals involved in line selection, and consider the issue done when each syllable follows the previous syllable without unexplained hopping.

Written by the indexing model from the issue text.