So, I am messing with my REST queries again, and was having some of these random errors. After some testing, it was determined that it appears that whenever a filter was applied to the title field, the filter will then refuse to work. Is there something that I missed that I will need to treat the title field any differently than other columns? It also seems like some other single-line-of-text columns are generating errors. So what determines whether if a column can be filtered or not?
As an example, I have been testing on the filter only, and doing statements as below over and over again on different combinations. It seems to me that some columns just plain doesn't work, and some just do not. All the columns I have issues with are single line of texts, that return an error 403. The columns that do not work with filtering included the ones that is being displayed in the result set when other columns are filtered, which seems to indicate that this is related to the filter function, but I am not entirely sure.
$filter=FIELD1 eq 'XXX'
$filter=FIELD2 eq 'YYY'