[Koha] Difficulty filling out accounting info

Good morning Ever since we were upgraded to 3.20.4 I have had difficulty filling out the accounting information for each item. I have found a work around for the books as I can can fill them out using the Uncertain Prices page then edit each item later, but I cannot do this for the subscriptions. Basically as soon as I enter the vendor price the rest of the price fields change to NaN (have no idea what this means) but the Budgeted cost and total cost fields are not editable. Then I cannot save because I get the error message -Total must be a number. Could anyone give me a hint as to what is wrong so I can tell our tech support where to look. Gratefully Ann Murphy Katikati College