Problem with foreign keys in phpadmin and on forms

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MySQL

I have three tables in my database. All three are tied together by a foreign key referencing the main table. Main table (CompanyData) has primary key (companyID). Two child tables (RepData and ContactData) each have foreign keys (ID_company) that references the main table's primary key.

CompanyData owns ContactData (OnetoOne) and CompanyData owns RepData (OnetoMany).

Now, I can physically add to each table using phpAdmin with no problem. However, I can not do it through a form. The form is working and was just fine before I added the relationships. Since then, I get:

"Cannot add or update a child row: a foreign key constraint fails (`reviewmy_jos1`.`dataContact`, CONSTRAINT `FK_contactid_companyid` FOREIGN KEY (`id_company`) REFERENCES `dataCompany` (`companyID`) ON DELETE CASCADE ON UPDATE CASCADE) "

What I don't understand, how could it work perfectly fine through phpAdmin when inserting the data but not when inserted through the form?

Also, if it makes a difference I'm using MariaDB.

What I have tried:

Works in phpAdmin when inserting data does not work in form when inserting data since adding the relationships.