Why are the bonus shares not visible in the holdings even though the company has issued it?

To be eligible for a Bonus or Dividend, the stock must be purchased on or before the day before the ex-date/record date. After the ex-date/record date, it usually takes around 15 days for Bonus shares to be credited to the shareholder's demat account, but the timing may depend on the RTA.

The shareholder will receive an SMS from CDSL once the Bonus shares have been credited to their account, but these shares will initially be credited under a temporary ISIN and won't be immediately available for trading. Approval for trading can take up to 4-5 days, after which the Bonus shares will show up on Kite. Until the Bonus shares are credited, the P&L in Kite/Console will show an artificial drop. Zerodha will only show the Bonus quantity once the shares are credited. If it has been more than 3 days from the ex-date/record date and the shares still haven't been credited, please create a support ticket below.

All the current and upcoming corporate actions can be tracked on this list (DOC).