BYDDY.US (ISIN/SEDOL: US05606L1008 / B3DTK60)
When looking at ADR’s (or other depository type interests/receipts such as ADS’s), the listing or trading of the actual ADS or ADR is irrelevant. All that matters is the qualifying status of the underlying shares. If the underlying shares are ISA qualifying (because they are listed on a recognised stock exchange or admitted to trading on a recognised stock exchange in the EEA, including the UK), then the ADR (or ADS) automatically qualify (regardless of its listing status).
According to the link (third link) below, evidence state the underlying stock (common shares BYD – CNE100000296) is traded on the on the Frankfurt Stock Exchange therefore, on that basis, the ADR should qualify for stocks & shares ISA inclusion.
BYD CO. LTD ADR/2 YC 1 Equity | A0X9JE | US05606L1008 | Share Price (boerse-frankfurt.de)
BYD CO LTD 0HKY Market Stock | London Stock Exchange
BYD ‘H’ Equity | A0M4W9 | CNE100000296 | Share Price (boerse-frankfurt.de)
BYD Company Limited (1211) Stock Price | Stock Quote Hong Kong Stock Exchange – MarketScreener