I found that, initially, except for a few outspoken individuals, most people are either afraid to say the wrong things and look "dumb" or genuinely do not think they have the authority to make a change or do not think it's polite to propose changes directly, bypassing their former "manager". They choose to stay quiet.
I have also found that this continues to be the main barriers, even after several years of implementation and that the change in this area happens slowly. Most governances are done by the same people over and over while a lot of people never bring up tensions. (This may be a cultural issue and we just have to be a little flexible, accept, and adapt as best as we can)
Several things that can help:
1. If you haven't completed the role coverage for your team, then you could just setup one role for each team member, and let the rest of the other roles be submitted through governance by each team member themselves. This is what we did in the beginning, so everyone at least have their own roles to submit in the next several governances, and practice bringing up tension, proposing, and processing the proposals.
2. Ask your facilitator to be extra vigilant in your tactical meetings and sense when there is the slightest confusion about what role is supposed to decide, or when people try to get a consensus on decisions, and guide people to add actions to bring those tensions to governance themselves. Don't let them delegate this to anyone .
3. If you're the former manager, if someone brings issues to be decided to you that you sense is a governance issue, keep asking them what they think should happen, without giving them your version of the answer, don't criticize whatever they propose, and just simply say "Good. Now bring this tension and proposal to the next governance". Ofcourse you can then react and object in governance itself.
4. Keep coaching people, if you're the "Holacracy coach" (and I assume you are. If not, create this role in governance and assign yourself to this role") that whenever they gossip and complain amongst themselves that things should be done a certain way, that it is a strong indication of tensions, either tactical or governance and just bring it to whatever next meeting they have if they are unsure. I normally add "if you decide not to bring this tension to a circle Meeting, then you should stop complaining". This is probably not the best advice, but I do it
5. Keep coaching people that they really don't need to have a proposal going into a governance meeting. All they need is a tension, and it doesn't matter what meeting they bring it to, just bring it to one. Proposals can be built in the meeting itself and others in the circle can help. This helps alleviate some of the concerns of looking "dumb", because most people fear that their proposal is dumb, but not so much about their tensions.
Even after doing all this, expect a slow process, so that you don't get too frustrated. It will get better, but it takes some time for people to feel comfortable with this new way. Some people will pick it up immediately. Consider this progress. The others will take a lot more time, and this is ok.