Problem with special characters

Hello

I put the following input in a dropdown menu
>=150µm

>=100<150µm

<100µm
than it gives problems
when i use

>=150µm
>=100<150µm
<100µm

it changes after saving the form in the first and block the next field

Is this a knowing issue?

How can i fix this?

thanks

Leo

https://ww.wp.xz.cn/plugins/visual-form-builder/