Who can help. I try to save complex hyperlinks in Multiterm text fields but receive an error message. The link works when the term entry is open but dissappears when the entry is closed.

 When I create a complex hyperlink in a Multiterm text field, an error message is displayed. The  complex hyperlink (example: eur-lex.europa.eu/.../ works as long as the entry is displayed, but as soon as the entry is closed and reopened the hyperlink disappears. Basic hyperlinks do not display an error message and are kept when the entry is saved, closed and reopened. Does anyone know a solution to this problem?