I think it's because you said you sold your IWDA+EIMI in SCB and rebought VWRA in IBKR, we assume you were just
transferring with no time lag. Apparently, you sold your holdings and are staying out of market while looking for a good time to buy again. So, I agree with
@highsulphur that you are subjecting yourself to market risks.
Just to confirm, you sold IWDA+EIMI (SCB) in one shot, but will re-buy VWRA (IBKR) over a few month?
Let me work your numbers backward. Assuming your holdings were worth US$100k, sold at 78.50 with an average cost of 50.4, that means your costs were actually about
US$64k (US$100k / 78.50 x 50.4). If you used the US$100k sales proceeds to immediately buy VWRA in IBKR, your
actual cost remains as US$64k as before (ignoring the sell and buy commissions). These are the costs you put in via DCA in previous years. It remains unchanged.
Obviously IBKR would not know about your actual initial costs. I can understand how you will feel to see your new portfolio in IBKR in red, if like you said it drops 20% the next day, but I think that misleads you. With a 20% drop, your new portfolio in IBKR would worth US$80k, but it is still higher than your initial costs of US$64k and you would still be in profit. The new cost price of VWRA does not matter if your sole intention is to switch broker and product (assuming your IWDA:EIMI is 9:1 which is close to VWRA).
Your decision to sell IWDA+EIMI (in one shot?) and re-buy VWRA over a few months can turn out to be a wise or not-so-wise move, depending on how the market moves. No comment on that, but I sincerely wish you good luck.