@Jakub Jagiela
Do you mean if you use Access Runtime 2016 open a database with conditional formatting rules which use Left function, the conditional formatting rules do not work?
I made a database on Access 2016 and open it via Access Runtime 2016, this issue could not be reproduced as following screenshot shown. The right one is Access 2016, the left one is Access Runtime 2016.
I would suggest you test on a English machine, which use English as the primary language for both Windows, Office Apps (Access).
Any misunderstanding, please let me know.
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