Thanks for testing. The LoST module uses core parser functions `../core/parser/parse_from.h` and `../core/parser/parse_ppi_pai.h` to get content of the corresponding header. When reproducing the error I saw that `get_from` and `get_pai` give different results. For `get_from` it is no problem to parse the header content of the examples above and to return the proper sip/tel uri used as HELD id, but `get_pai` also returns the display name.
I will implement my own parser, although a consistent behavior of the core parser functions would be the better option.