Measure corrupted issue after saving score

I have an issue with attached score. Everything seems to be ok, but when I save the score, and reopen it again measure # 30 appears corrupted. I notice that when this occurs, 29th 4/4 measure appears wrongly changed. I had wroten 4 semiquavers sixtuplets, but after saving the score and reopening, I notice that 29th measure contains two semiquavers sixtuplets and lefting semiquavers appear ungrouped, so part of those semiquavers get shifted to measure 30 and this is why measure 30 gets corrupted.
There are more measure with 4 semiquavers sixtuples on 4/4 but this problem only happens on measure number 29.
I have tried to create a new score , select all measures from previous score and paste on new score, but the problem occurs again.

Could you please help me to understand what is wrong? thanks in advance.

Teresa