As many mobile users have discovered, the mission 'Pier 69' presents a story-halting bug coupled with a disappearance of the save game icons. The bug occurs solely due to select phone calls left unanswered which then bugs up the script and leaves out key features to moving forward in the game. Follow the steps below and everything will play as intended.
First thing, you must begin from a save game before the mission 'Jizzy' for proper effect. If you have no save game prior to this, you'll have to start a new game to progress in the story
- Once you have purchased Zero's place, you must wait for his call. This unlocks Zero's mission. (This is not necessary as it isn't directly story-related but if you receive no call from Zero after the purchase, your game will display problems down the track)
- After you have completed 'Jizzy', wait for Woozie to call you. This unlocks Woozie's mission.
I experienced the two problems above on my first two playthroughs. I received no call from either person the first playthrough but received one from both on the second playthrough. 'Pier 69' was bugged both times.
The point is that these calls can be accidentally skipped and the game may or may not run fine but can either show major cracks in the story down the line or leave you at 99%.
- After finishing the driving school, wait for Jethro to call you. This will unlock the races.
I only received this call on the third playthrough which, incidentally, is the playthrough in which 'Pier 69' began working.
Potentially the most important
- After you have completed 'King In Exile', wait for Cesar to call you about the drug and cash shipments between the Loco Syndicate and LS. The initial call will detail what shipments to expect and when. Any calls from Cesar requiring you to pursue the courier (Mondays, Wednesdays, Fridays or Saturdays) don't require completion.
As for users having trouble with 'Sweet's Girl', I would assume the same problem is happening. Somewhere, you missed a phone call or two before that mission. I can't say where but you most likely have which is causing the mission to bug out as it has with 'Pier 69'.
These issues are most likely only showing up with the mobile release due to the expected complications of transferring such a large and diverse game to a mobile device.
Sit tight, take your time and enjoy the story.