Data on ALL multivalue field became single value

Hi masters of LN, need help in our concern:We have a confidential database, with appropriate author/reader field that are suddenly became corrupted:

from Field Flags: SUMMARY NAMES, instead of:

Field Flags: SUMMARY READ/WRITE-ACCESS NAMES.

Certain docs became visible to general users. We thought that only the author/reader field became corrupted, however upon further checking, we’ve noticed that ALL fields which are set to handle multiple value became single value

from:

“value1”

“value2”

became : “value 1, value2”

Any help will be fully appreciated. Thank you so much…