Try to add an empty security. The Portfolio Performance (built-in) is just for stocks and yahoo is a bad source for european bonds.
Italien bonds (BTP) are described here: Investing.com is not allowing anymore to scrape historical prices - #7 by ProgFriese
For IT0005441883 the URL is https://www.milanofinanza.it/Grafici/GraficoStorico?stockCodeRT=2c73&codiceStrumento=1ac&nome= but please find it by yourself on Btp | Milano Finanza
GR0133011248 can be found for example at onvista or lang&schwarz
URL https://www.ls-tc.de/_rpc/json/instrument/chart/dataForInstrument?container=chart1&instrumentId=554520&marketId=1"etype=mid&series=intraday,history,flags&type=&localeId=1
Date $.series.history.data[*][0]
Quote $.series.history.data[*][1]
If you like to use onvista please read How can I add this bond with on PP? - #4 by ProgFriese
More Infos in general how to find JSON-sources: I want to understand how to get historical pricing data via JSON
