i had similar problems, not all dashboards would clone some did some didn’t, the problem was if the names exceed 24 characters and strict mode on mysql was enabled, which is on by default in mysql 5.7+.
The problem is that when strict mode is enabled and you supply a varchar fields value that’s longer than the field can handle for example varchar(30) field and value is 40 characters, the sql statement will fail. if strict mode is NOT enabled it will cut off all extra characters and the sql statement will not fail
to rule out it’s the same problem see if doing this https://www.euperia.com/development/mysql-fix-field-doesnt-default-value/1509 fixes the problem as it fixed all problems i had with this.
see the other issues i had related to this here Emoncms 9.7.3 can't clone dashboard + toggle published problem